Numbness at night?

Bree • I`m 27 yrs old and have one son (8). I just had our second. Not sure if we're done or not.
I sleep on my sides like I'm supposed too. But for the last couple of nights I have literally woke up multiple times with each side going numb (minus my face). And then it just hurts. I have my big pregnancy pillow and I sleep with it between my legs? I just don't know why it's doing this? Any ideas what it is or suggestions to help it?