DECREASING WEIGHT OF4 day old KITTEN..needs help..

My kitten isn’t drinking milk today and the weight decreased since the other day, from 80 to 70 then today is 60..and i’m very worried about what’s happening.. S/he is an abandoned kitten..The other two died because they had health problems, and so far, this kitten is the only one surviving.. I have no access to vets because i’m only a student. I really need help..