Amy, thats horrible! How bis is Avid?
What I would do is keep the water as perfect as you possibly can, get some salt or melafix in it, and put some neosporin or any other antibiotic cream on the spot. Clean it with hydrogen peroxide before though....I don't see any reason why Avid shouldn't come out of it.
Heaters are a touchy thing. The only tank where the fish fish could squeeze behind the heater is my veiltail tank, and I have not attached the heater to the glass there. It just dangles from the top in the middle of the tank.
Good luck with Avid, and let us know how he is doing!