Blood test positive for strep,but i don't remember having strep throat recently.where could it come from?10 days on penicillin,should that clear it up

Hard to say: I assume you are commenting on a strep antibody test, since you would be very sick with strep in your blood. Adults can have ASO and similar tests at higher than expected levels form rather insignificant illnesses. A single skin infection, minor sore throat, or other issue can push up a titer. In the absence of symptoms it is viewed as a curiosity, not a sign of active disease.