IUD poking boyfriend?

Katherine
Hi!
I have had an IUD for 9 months now.
After four or so months, I tried to feel for the strings. Never found it. So I went to the doc. 
She said it's really high up and I probably won't be able to feel them myself BUT it isnin place.
Now, when I'm on top of my boyfriend having sex, he'll randomly shreek of pain and say its poking him.
This has happened two times... Is that normal and should it hurt?
I have another ob appr.  butnIm wondering if anyone else has experienced this.