I care for several feral cats ..the oldest tom was recently tnr.. Recently I've noticed that the fur on his back in one small round spot and a larger area on his lower back down to his tail is raised an inch above the rest of his fur..he seems healthy except for some discoloration under his eyes...now occassionally he acts as though something is biting the area and he runs away and even vocalizes..I'v been giving him Capstar in case it is a flea infestation which hasn't seemed to work...Is it an infestaon of some sort or a skin condition or something else ?.