I have a 1 year old male cat, fixed. I noticed tape worms last week and I treated that. No blood in stool.

I'm confused - you say "blood in stool" and "no blood in stool." What is the situation?

If there IS blood the cat needs to see a Vet - no one can diagnose without actually seeing the cat and it could be any number of things.

There is blood in the stool, is there any over the counter pill I can get him?

No, there is nothing over the counter. It may be colitis, which is remedied with a pill. You should call your vet and let them know that shortly after worming him you began to see blood in his stool. Let them make a recommendation--the vet may want to see him or the vet may just want to take a look at a stool sample.