confused...important question that needs to be answered

I wrote a message earlier about a sore that I had descovered on my penis 2 weeks after i recieved oral sex from a girl. The girl has been tested since then, and the results were negative. I also talked to an std testing facility over the phone, and they said that it, was "virtually impossible to obtain herpes if the girl did not have any cold sores present in her mouth"...which she didnt, and she claims she never gets them. First of all, I would like to see if anyone can shed light on this statement because it seems as though all of the internet research says that a person can pass an std without showing signs, and that you can recieve genital herpes by oral sex, but it doesnt answer if it can happen if both occur.
My other concern is that the sore is still not fully healed. It has gone down in size, and is not as red, but it still seems to resemble a cold sore or ulcer. Theres an outed shiny red ring, and a small white spot in the middle. This event hapenned on New Years, and I discovered the sore for the first time about a week after. However, during the oral sex, I felt a sharp pain from teeth or something, so this may have caused a cut which got bigger and wasnt noticed until later. If this could have caused the sore, why has it been so slow to heal?

These questions are plaguing my mind, if anyone can help I would GREATLY appreciate it. Tweet