Help 😫

I just entered the third trimester and I’ve had a very uncomfortable pain on my left side right under my boob that started the last couple weeks of the second trimester. I’ve also had the pain in my lower back on the left side right above my butt. Is it normal? Is there any way to stop it?? It mostly happens at night when I’m trying to go to sleep and I’ve been trying to put off buying a pregnancy pillow cause I figured regular pillows would work but I’m about to give in and buy one😫