I Rarely Wear Underwear To Begin With, And Keep In

I rarely wear underwear to begin with, and keep in mind my bf and I had had sex the night before (a little bit drier and rougher than normal) and I had just shaved the day before and had some stubble from regrowth. So yesterday after taking my shower I put on my jeans (that I always wear) and went about my day, an hour or two in to the day I started feeling like they were rubbing and pinching me in the groin and on the outer surface of my right labia and the inner crease (underwearline) of my leg on that large tenden....upon examination there were no blisters but there is what looks like friction burn spots in the spots it was feeling irritated. I did find that two of them did in fact have in grown hairs which I removed. My question is this. Could the rubbing of my jeans have caused this and the two ingrown hairs or were those two just more irritated be cause they were already there?? Or could it possibly be an allergic reaction to soap or perfumes from the detergent or softener on the pants or in the shower? And is there anything I can use topically to put on the affected spots?