I've had my period every two weeks for several months. Recently, I noticed that the inside of my vagina seems swollen/thicker. It's hard to say if the thickening is a lump, or just thickening. I went to the gynecologist and she told me to have a transabdominal ultrasound performed. The results came back normal. Is it possible that there's something there, but the ultrasound didn't pick it up? What is this thickening/lumps?