Shoulder pain?

Sylvia
Okay so every time my husband and I have sexual intercourse I have this horrible pain in my left shoulder sometimes during but mostly afterwards. I will be 29 weeks tomorrow and have been falling this pain for the past 6 weeks.  Anyone else experience this?? My husbands says I need to stretch before we have sex but I've never had to before, so why would I have to start doing that now? 
P.s it looks like I'm spelling shoulder completely wrong maybe it's the prego brain??? Lol