Woops, I should add: The small scabbed area was on the shaft of the penis, on the underside near the bottm of the head. Not on the head itself. Thanks.
The only symptom you describe that sounds like it could be STD-related is the penile lesion that scabbed over. As your subject line suggests, herpes is the greatest concern, and that disease explains the large majority of leions like you describe--much more likely than trauma from masturbation or other traumatic lesion.
If you have herpes, you probably didn't acquire it from the December exposure you describe; and I don't think the other symptoms (tingling, rectal itching) are related either to herpes or to the December event. It's worth noting that herpes can mimic UTI, so it wouldn't be particularly surprising if both you and your girlfriend have genital herpes. I wouldn't bet on it, just raising the possibility.
"Tiny red bumps" and "white patch" suggest yeast infection--which you and your girlfriend also might be sharing. Yeast and UTI also can be confused with one another.
I suggest you and your girlfriend both be evaluated by an STD-knowledgeable provider, including blood tests for HSV infection (HerpeSelect HSV-2 test, HSV-1 optionalt; see many other threads about the right and wrong kinds of HSV blood tests). I often recommend people go to their local health department STD clinic, but many such places unfortunately don't routinely offer HSV blood tests, so you might call ahead first.
Good luck-- HHH, MD