What Causes Itching On Penis Head?

I have a slightly irritated penis head, I had something similar about 6 months ago and went to the doctor and he was sure it wasn t hsv2 and I had two blood tests and both came back negative, so I went to another doctor and told him my symptoms and he was also sure that there was no chance that It was, saying that i would be in sufficient discomfort etc, but now I have a slight itch and a bit of discomfort with no rash, no blisters, no burning when peeing etc..... is there anything else it could be