Sometimes when we're having sex, it feels awkward. It feels like there's not a whole lot of room in there, like he's hitting something.   
I know your cervix shifts position throughout your cycle. Is that what I'm most likely feeling? Or is there some other explanation?
Google kind of fails me. Help (or flame) me BOTB. 
Re: Because it's Tuesday(k)...
When your cervix is low it's entirely possible that his penis is whacking it while you're bumping uglies.
Hahaha. This is how I wanted to describe it, but I thought it wouldn't be very clear. Thanks for confirming my suspicion CB!
I agree with CB. Also if you aren't totally aroused, it can feel like something is hitting something else and sometimes hurt too. Ask him to get you in the mood a little more beforehand (ie: naked back massage- its a win-win)
SAHM to 4 kiddos... K (5/05), N (4/09), C (11/10) and Baby A 1/13/14
While I love a good back massage, the latest case definitely wasn't a problem of getting in the mood.