Multiple Joint Swelling

Hello,
I have a 2 month old kitten who recently developed a limp. The vet found that she was running a fever and gave her antibiotics because he said it was an injury which had become infected. Tonight (two days later) she has developed swelling on two other legs (one on a foot and one on a hip). I am worried the infection is spreading. She also has a swollen abodomen. Are there any other illnesses you know of that would cause these symptoms? Please think good thoughts for my precious kitten!

If she were mine, I would get her to the vet and check her in until she gets well.

Hi there,
I took her back to the vet, who is concerned that she didn't respond to ampicillin. She also had a bump on her neck caused by an allergic reaction to the ampicillin injection. She is on another antibiotic, but he's really unsure of what is causing this. Has anyone experienced these symptoms before? Please let me know!