Need help with wounded rat snake

[Seijun]

Hi, I need help with a Black Rat snake that I found today. It was really cold (starting to snow) and I found the snake lying by a hole in the ground. I think it got mauled by a mink or small dog (my mom thinks mink because it was next to the mink hole). The snake is pretty beat up around the head and neck, and there is a puncture wound a little less than halfway down his length that's about 1/4" across (the snake is about 3' long). I brought him home and fixed up a terrarium for him with a heat lamp, water, and newspaper with some bark to hide under (I was going to use mulch but I didn't want it to get into his wounds). I didn't want to let him go either because it is going to get colder and there are no safe places here that he would have the strength to crawl into. He is alert and active now, but I am worried that his injuries will get worse. What can I use to help heal the snake's wounds, or at least try to keep them from getting infected? I don't have money for a vet or fancy medicine, so I was wondering if there were any remedies that were fairly cheap or that could be easily found that would help. (If it would help any, I can get pictures of where he is hurt at).

~Seij