Need Help Kitten Gets Seizures

I need help, if anyone has a furry friend that gets seizures(I will get into more detail about it) please let me know how the process was, how you found out what caused it and how to deal with it now etc.(I’d appreciate any story really or help whatsoever about cat with seizures) I got to adopt this roughly 10 week old beauty from an animal shelter 3 days ago, where he was dopped off after being found abandoned apparently. At the animal shelther they asked me whether they should castrate him before I take him home and I replied not yet, as I felt he was still too young for it and that I’d simply come back once he’s older. When I came to pick him up two days later(as I wasn’t able to take him immediately) I was told they had already castrated him. I found this odd ofc, as I especially said no to castration so early but important to me was he was happy and healthy, which he definitely seemed to be. When he arrived at my house he was also fine, normal kitten behaviour. As I have a busy shedule I couldn’t spend as much time as I wished to but still especially put in several hours a day for playing, cuddling and so on together. The next day he was left alone for 3h and when I came back to check on him I found him with foam around his mouth, an empty water bowl(I filled it just before leaving) and a puddle on the floor. Ofc I immediately looked around what could have caused the foam, any poison or something but everything is completely kitten safe ofc and there was nothing that could’ve caused it so I figured he foamed from the mouth out of excitement or something similar as he seemed perfectly well apart from the foam. And fine he seemed the rest of the day too but then the following day it happened, I spend two hours simply playing and cuddling with him and then went out of the room for aprox. 40mins to eat etc. when I suddenly heard a lot of running around and scratching, it sounded as though there were suddenly two cats in there fighting. So I ran into the room to see what’s going on to find him on the floor, twitching uncontrolably, in an odd position not being able to move apart from shivering/twitching, foam coming out of his mouth, not being able to move, eyes not focusing and I think not being able to breathe. This lasted for 10 more seconds until he suddenly became himself again, then he suddenly looked around very disorientated, not remembering anything from the seizure he had just a moment earlier. I wanted to go to the vet immediately but had no possibility to do so as it was already passed the vets closing time. after the seizure he immediately went to his food bowl and ate a lot of food almost fast enough to choke on. he drank some water and came to me and fell asleep on me for 1h. when he woke up he walked around the room and suddenly started to hiss at me(which he’s never done before) and as expected he started his second seizure of the day which involved him starting to foam from his mouth again, twitching again(strong twitching/shaking), running around in a circle uncontroably, peeing and pooping. It’s very frightening to watch the whole thing. It lasted again for aprox. 15 seconds until he was himself again. At this moment I asked my mum to check if there really isn’t any vet open anymore but to our luck there was one nearby thankfully. So I grabbed my thinks and just before being able to leave he got his third seizure, which again started with the hissing and then went on to the foaming, twitching, running, pissing… this time I put a blanket around him and I think it helped as this seizure lasted much shorter than the previous ones. At this point I was freaking out myself as I just wanted to help but knew there was nothing I could do. So I did the only thing I could and put him into his transport box and rushed to the vet as fast as possible, in the taxi I noticed him getting another seizure but I couldn’t see much of what was going on. I reached the vet and he seemed ok, the vet asked for details and I explained everything that has happened, the vet asked if there was any chance of him having eaten poison or me using flee spray or washing him. But I did absolutely nothing unsual, all I’ve got to do with him until now was giving him water and kitten food and playing and cuddling with him. The vet gave him two injections, one anti biotic and one to calm him down a bit. I was asked to keep the little kitten there over night as it’s better to keep him under observation and I said ok, I was told they’ll call me the next day to tell me how he’s doing. as I couldn’t wait I called in the moring but they didn’t know much as yet and said they’d call back in the afternoon once they know more. in the afternoon I called again and the vet said the kitten has had 3 seizures so far and it’s unsual at such a young age to get that many strong ones. And that any seizure could be fatal and cause either kidney, liver, heart or brain failure. They asked to keep him one more night for observation and also because he needs injections every 6h. I’m supposed to go there tomorrow and talk about how to proceed. I don’t know what will happen, the vet doesn’t seem to know what it is. So, if anyone has gone through any similar experience with their kittens/cats I’d love to know more about it, any suggestions to what it can be… Any help really is appreciated. I just thought I’d give it a shot and hope someone has gone through the same/similar thing and has any suggestions/ideas of how to deal with it… Thanks a lot in advance.
P.S. I don’t know if this will help but my fur ball is fully black with heterochromia(odd eyed cat, one blue eye and one green/hazel eye. Very rare.) Maybe they are more sensitive, I don’t know 🙁 I also always thought he kind of has a bloated belly but the vet said he’s in perfect shape…