Can you send out a picture? There are different types of infections requiring different treatments. Most can be cured by cleaner conditions, warmer water and good food. The alligator immune system is amazing. One of our 7 footers had his front arm ripped off (by a unfriendly female) and he healed up quite well. We are thinking about getting him a "peg leg" so he can get around on land better. A picture will encourage more responses from this forum. If its bad a Vet is still your best bet.
Good Luck.
Bob-B