STD? what should i do?

abt three weeks ago i had sex with my boyfriend and he came inside me as i'm on the pill. before that, he's been cumming inside and and ive never encountered any problems. until 3 weeks ago when i felt irritated and itchy in my vagina, so i treated it with a thrush pill and it cleared up after a week. now recently, i had sex with my boyfriend and he came inside me again, and i'm dealing with the same irritation i did the last time. should I test for an std? or just take another thrush pill PLS HELP