What Causes Burning And Itching In Vagina?

Hello I recently had sex with someone and it burned when he ejaculated in me and when I swill owed his cum while giving him a blowjob. My vagina is still burning and quite itchy I did a vagisense test and it was negative so I started a yeast infection kit. Was I right to think its a yeast infection?? I must also factor in that I am on Biaxin for bronchitis