Husband has bleeding when he has bowel movements and it seems to get worse after he takes painkillers.... any idea why?

Bright red blood with BMs would be from near the outlet from a fissure or hemorrhoid. Darker/maroon or blacker blood would come from higher up where enzymes had a chance to discolor it. I cannot link the painkillers to it beyond making him constipated & a set up for a fissure.

Any abnormal bleeding needs to be investigated. Bleeding from even a benign cause such as hemorrhoids can result in anemia. It is imperative that your husband see a doctor.