possible skin problem.

I am curious if anyone else had this problem...
I can brush my cat so that his hair is almost perfect and within a few days his hair on his back gets rough..knoted up....if I touch his back, his back tightens up...looks like it is very sensitive or painful....
I even cut all the hair off on this section before to see the skin and see if it knots up and it grew back and knoted up....I figured I would ask here before going to the vet because it will cost a minimum of $100 to walk into the vet.

Any idea's....

Have you tried brushing him daily to prevent it knotting back up? It may be that he can't easily reach that part of his back during his grooming, due to age or weight issues.

You may be right....Perhaps because It is not brushed daily it is knotting and pulling on the skin...I will brush more often to see if it helps....Kitty won't mind...he loves to be brushed until he tries to eat the brush.