A blister that scabs over sounds like herpes. You have to request herpes testing. It is not automatic in full screenings. So, i recommend you do so. Since your blister has scabbed over, you will need to get a blood test. And your boyfriend should as well. I know you don't want to go to the doctor, but you could spread the virus to other people even if you do not have any blisters present. Please go so you can be sure it is or is not herpes.
For any further information on herpes, please visit the herpes community.
Then I don't see how this is STD related if both have tested for STD's and are negative.
it actually seemed to have gone down today its just scabbed over now.
Bumps can be many things often not STD related. Has your boyfriend ever tested for STD's?