Are there any veterinarians out there who can answer a question for me? (sick cat)?

my poor little guy has not eaten or drank on his own since wed night. i took him to the vet on friday morning and the vet did a VERY brief exam and said that since there were no other symptoms but the lethargy, lack of appetite, and fever (103.0) that he didnt think it was anything incredibly serious. he said he thought maybe he got into a cat fight and may have an infected wound or possibly because he is an in door out door cat ate something that was infected and it made him sick. he gave him a shot of amoxicillin and sent us home with some liquid amoxicillin. Ive been having to force feed him since late thursday evening and he still wont eat on his own. yesterday when i force fed he did not fight me at all. he was so weak that he just couldnt. today has been a completely different story. he's gotten well agitated from me syringe feeding him water and a mixture of plain yogurt, hills science diet wet food, and water. he has also switched spots more frequently and asked to go outside for the first time in 2 days. i brought him out for ten mins and kept a close eye on him as i figured it might lift his spirits. now my question is, is him getting angry about the feeding, asking to go outside, and moving about a bit more (and he had a bm this morning and went pee) a sign that he is starting to feel better? im just still worried because while logically i know these are all signs of him getting his strength back i still can put my mind at ease because he will not eat or drink on his own. how long would be the average time for a cat to start eating after antibiotics have been administered? should i still be concerned or does it sound like he is on the mend? any advice would be greatly appreciated. thank you so much in advance.