It is known in our house as knitting needles up the fango - I had it with my last two. I didn't have any infections - I just assumed it was becasue of the stretching and loosening and all that. Possibly baby pressing on nerves. Probably something to do with hormones too.
Have posted this before when someone else asked the same Q.
Is it like a sharp knife up your fanjo/perineum?
I had this with a hormone coil (Mirena) and now earlier in my pregnancy. On top of that I experienced cramps which worsened and subsided over 4h. After a while the stabbing pain returned. I went to 2 docs and they said it's the hormones. The Mirena mirrors hormones you'd have in pregnancy and since I was obviously pregnant it seemed to have come back. Sitting or standing I felt a knife went up there. Docs said not to worry, it will pass. And it did.