My 7 year old has had a red anal rash for 2 months now. dr. has treated for streph, yeast infection, and now testing for pinworm. what is going on?

Maybe...: May be a form of psoriasis which may respond to a cortisone type cream. Also rare sign of colitis. Ask your pediatrician.

Can be difficult: Pinworms just produces an irritant rash due to the glue the PW eggs are laid in around the anus. Sort of like poison ivy. Simple tests /treatment & anal application of hydrocortisone cream can help. The kid may be caught in an itch/scratch cycle where the urge to itch it takes over & prevents it from healing. Food allergies can also do this.