Sick Kitten

We brought our 8 week old home and went to the vet the next day with a URI, sneezing runny nose caughing and wheezing. Vet dewormed her and treated her for fleas and mites, and also put her on antibiotics and drops for her eyes. After about 2.5 weeks she was seemingly healthy. No more runny nose or watery eyes, clear breathing and playing like any other normal kitten. And then she stayed in bed all day only getting up to eat or potty. This got worse the next day so took her to vet on monday.. They have no clue what is wrong with her, they treated her for inflamation. We have to take food to her and put her in the litter. This is early Wednesday morning and i just dont see any improvement. We are giving her mothers milk and some pedialyte daily. She does eat some every 4 hours or so.....