I'm 30 weeks this coming Tuesday and some days my ears feel like they need to pop/they're a bit blocked up, I can't hear people as well but I can really hear my own breathing. Seems to come and go!
If your back is hurting off and on and your belly gets tight when it hurts you might want to just let your dr know.
Could just be Braxton hicks, I get mine in my back sometimes and they hurt pretty bad.
Try eucalyptus shower gel/wash for the stuffy nose/ears. I started doing that every morning and I rarely have plugged ears/nose now