I Had A Surgical Abortion Three Weeks Ago. I Had

I had a surgical abortion three weeks ago. I had protected sex two weeks after the procedure, which immediately caused a burning and itching sensation I had never felt before. A couple days following the burning and itching, I found blisters on my vagina. I don't have swollen lymph nodes or any sign of infection. Also, I have never had herpes symptoms before and I've always tested negative for it. What do you think could be causing such blisters?