You seem to be following a common misconception in medicine. In med school they taught it to us in Latin as:
Post hoc ergo propter hoc
The literal translation is "after this, therefore because of this".
The reason it is taught in medicine is that it's a logical fallacy which states "Since event Y followed event X, event Y must have been caused by event X."
While it is true sometimes, ie I give you a medicine, you get a side effect, often it is not true. For example, Bells Palsy was thought to be caused by having a bath and being exposed to a cold draught. Doctors would ask patients "Did you have a draughty bath" and they would say "Yes". The problem was this was true for a whole lot of people so although one event seemingly followed the other, they were not related.
Anyway, you seem to relate your issues to exposure to a girl and unprotected sex. While you can certainly catch all sorts of diseases from unprotected sex, you are very unlikely to catch Hep C and if you have Hep C we can detect that very very very efficiently with PCR. If your PCR is negative then we (and you) can be confident that is not the cause, and that treatment of Hep C will have no benefit.
So while I have no doubt the problem is exactly as you state it, the cause of the problem is not. Once you can accept that, we can move on to looking for the real cause of the problem...
A complete physical examination and blood tests would be the logical starting place.