What Causes A Recurrent Bump On Vaginal Wall?

hello doc. i have this bump that keep reoccurring on the back of vaginal wall. first time i got it , i immediately went to obgyn. he said its a pimple just apply hydrogen peroxide. it burst with yellow smelly pus. he later gave a pop smear. the results were fine. the bump came back again. i used the hydrogen peroxide and it burse. last month i took a aids test and std tests. they all gave back negative. but i have realise everytime my partner does oral for a long period of time i get the bump....i am becoming scared! what do you think?