Emergency cat question!?

i found a kitten (seems about 6 weeks old) outside my door step 2 days ago. i noticed its face was covered in ants so i took it right in and cleaned it up and snuggled it up in a warm blanket and bottle fed it powdered milk for kittens. the kitten seemed quite alright yesterday, but this morning i was cleaning it up with some wet towelettes and i noticed strings of puss coming out of its hole. its hole seems swollen and blistered. i'm really worried. the kitten doesn't do much. it just sits very calmly, but obviously something is wrong with it. so, my question is can i do anything here at home to fix this problem? if not, what is the estimate amount i would be charged at the veterinarian for this?