i have a white bump on my penis

hi. i am 23 years old and beleive it or not but the one and only time i have had sexual contact is i had oral sex performed on me.  im a male. and it was over a year and a half ago. i have had a little white bubble really tiny thing on my penis shaft its been there for over a year and now im concerned i tried popping it but little white cream lookin puss or w/e comes out but eventually it comesback its really tiny. now i had a blood and urine test done and im negative to all std's the only one unsure about is genital warts but i dont think it is because it doesnt look like the pics ive seen and i also was told genital warts dont have fluid come out of them. no discharge,no itching or burning or pain or anything its like its just there. i went to the doctor to get it checked out and he told me it was just a basic bump and should go away with time..now im sitting here 6 motnsh later like wtf? its still there. im wondering if anyone else has had this issue and if so is there anyhthing i can do on my own or request to a doctor to get it fixed.