I am not a midwife, but i can tell you my personal experience.
Has she considered vaginal hemorrhoids? I know it sounds ugly (really it is) but I had just that experience you described with my third pregnancy.
The pelvic area has such an increase in blood volume during pregnancy, and some people develop varicose veins in the vaginal, and external genital area along with it. It feels like alot of achy pressure and can be quite painful later on, but really little can be done about it. Cold compresses, regular exercise, and then staying off your feet, preferable laying down, not sitting on your bottom can provide some relief.
I could be way off, as i said, i don't know her situation, but this was mine.
Hope she feels better soon