that's interesting that u mention blood vessel constriction.I started getting weird sensations in my hair a month after iud inserted.it was in the same spot and started to think it was the nerve endings.now it's in my face.it's like the skin tightening around my eyes and cheeks,mostly on the right side.i wonder if it's the blood vessels constricting from extra hormones.got the iud out today so will be hoping it will stop the strange skin sensation and my hair loss (50- 100) every shampoo.