For some reason, TMS or otherwise there is a lot of tension there. Couple of suggestions:
1. Try progressive muscle relaxation before sleep and once or twice during the day and see if that helps. It combines mental and physical relaxation to release mental and physical tension. See this video from Johns Hopkins.
2. Do some simple pelvic floor exercises to get those muscles moving and release tension. You can find them on YouTube or work with a physical therapist to make sure your form is correct. These are meant to release tension, so do them gently to help your pelvic floor muscles relax.
Try these two for a week or so and see what happens.