Help! My cats left paw to elbow is completely swollen!?

My cat for about 4 days his whole left "arm" ( I know cats don't have arms) is completely swollen! He's limping and not eating well.. He's not in any pain but it's very stiff and he doesn't move it when I compress it lightly or anything. Right now my family and I are going through realy tough economical problems and I can't take it to the vet because I really don't have the cash but would If i did.Please don't think wrong of me my mom recently lost her job so I'm not really economically stable but I really do love this cat. Many friends say it could be an infection.. Any suggestions? Does anyone know atleast of a low budget vet in the Miami area where I could take him if I scrape up some money quickly? Any advice would help thanks.