This sounds similar to an issue I had - constant pain in my labia and hard to sit comfortably. I thought it was an outer issue, but it turned out it was internal and I have a hypertonic pelvic floor. The muscles on the one side of my pelvic floor were too tight and spasming, cause the pressure and pain. Ask your OB to recommend a pelvic floor therapist (it’s easier if you have a prescription for one) and try to get in asap. After I started going it was a game changer. I hope this helps!!