Vaginal dryness

Okay so I had unprotected sex (I know this was not the best move but was heat of the moment but I am on the pill although I know that doesn’t protect against STIs.)

Anyway this was a few months ago and ever since I just can’t seem to get wet down there. I never had this problem before and it makes sex very uncomfortable.

I know I can purchase lube but I want to actually fix the problem. Any suggestions as to what I should do?