OCD rears its ugly head!

So our aspie has a "newer" obsession. In his words, "when I walk, I have to erase my footsteps." When hubby and I ask him why, he replies, "because my brain tells me to repeat them, so I tell my brain to erase them." So he does. Last nite was awful. Every step LJ took, he repeatedly exclaims, "erase, erase!" It breaks my heart. At only 5 and a half, he should not have to endure such things. So we are left with the question, what are we to do? We can tell him he doesn't have to do it and discourage him til we are blue in the face, but so far that does no good. How can one so young argue with his own brain? We were told we can medicate him, but as of yet, we are uncomfortable with that idea. So now what? I will say on the bright side, since this obsession has taken precedence, he is less anal about hand sanitizer, and licking his face raw. He is still a germ a phobe, but he's not using hand gel til his hands are raw, and throwing temper tantrums over it being out of reach. When I was a teen I often found myself obsessing over death and house fires. Due to my age, and maturity, I was often times able to talk myself out of these worries. How though, can one so young cope with such things and to a much greater degree? What must go through his little mind to make him feel the need to "erase" EVERY step he takes? I guess I will never really know, but I'd love to be able to help him. As a mom its my job, and I can't stand feeling like there is nothing I can do. I guess if it keeps on, hubby and I are going to have to rethink meds, because our son is too young and innocent to have to live this way...