How Can A Boil Near Anus Be Treated?

Hello, I think I have a Boil near my Anus, that appeared last tuesday morning, Before that I had some bad constipation, and I also live with a Roomate who does'nt keep things very clean here and I might of gotten infection there. About fifteen years ago, I had a Cyst down there that had to be lanced and removed. Recently my Diet has not been very good, and I have'nt been eating very much Fiber. I do not have Insurance, but will this possibly go away if I soak in very warm baths (with Epson Salts), use a Heating Pad, Amoxicillan (I found at the Pet Store), Zinc Tablets and drink plenty of water. Were I live, there is a Medical Clinic that is quite reasonable, that I think I could afford to go to, but I'm hoping they could take care of it there and lance and treat it, because I think that would the only I could afford to have a Professional help me with this. Thank you very much for any advice you can give me. Steve