Single Painless Blister

Hello, about 7 days ago I noticed a raised lump on my shaft right under where the penis head is (I am uncircumcised). Its skin color and has a very small spot that seems yellow, like possibly crust. It hasnt spread or caused any pain or itchiness in the week ive had it. I have had one sexual partner these past 7 months and havent previously had any issues. I have been panicking quite a bit. Today I went to get it checked out. The doctor is unsure though he said he would treat me for herpes. He said that it could be herpes but he is concerned because its painless, and not itchy. He also said the same about syphillis but there is a lack of pain and no weird substance coming from my penis. I also asked for HSV IgG test so that we can be sure. I am waiting on the results, but my mind wont stop dwelling and can hardly wait that long (Not that I actually have a choice). I can already guess the most likely cause according to everyone is herpes and I can accept that if I have to, but for my sake can anyone tell me what the problem could be ASIDE from being an STD/STI?? I would show a picture but I am not sure of how to do it. So if you need it to help me out please let me know. 

Possibly an irritation or something! 

Hey i almost have the same story as u. So if u can help/update me with ur case it would be much appreciated

I have these two small blister looking bumps for two months on top of my scrotum and 1 in the middle of my pubic hair area. They're completely PAINLESS. I do not feel anything. And then i got this big bump recently that burst into blood that had just mild pain when presuure is applied.

So im worried. So can u plz help