Lol, it's most likely your little one has decided that he/she likes to have their feet/head up in mommy's ribs.

The best thing to do is try to get baby to move positions this doesnt always work but I find it helps

stretching go from side to side arm over or try to touch ur feet I know its impossible but sometimes it helps

take deep breaths, when you breathe in you ribcage/diaphragm moves up so hold ur breather for 10-20 sec and do it a few time or while stretching

put heating pad on ur side to relieve some of the discomfort

hope this helps
jess