Feline Immunodeficiency Virus

[nem&dash]

My cat, who was a stray, had a sore open up by his tail about three weeks after I took him in. The vet said that it was most likely just a bite from another stray cat and that it should heal up in a week or two. It healed fine but then a few weeks later it reopened. The vet said that if it cropped up again, surgery might be needed but it healed fine. About a month after the last episode, another spot showed signs of infection but never opened. It went away after a few days but now, about another month later, its back again. Is this one of the symptoms of FIV? I didnt have him tested when I got him because not only was I a little overwhelmed by the sore and related costs, but he is my only cat, strictly indoors, so I figured it could wait. Now I am really worried that he has FIV But he has a very healthy appetite and that seems to be one of the main concerns. Any thoughts?