Chest pain while sleeping

I’m currently 32 weeks and 3 days. Lately, while sleeping, I occasionally wake up to find myself on my back and have slight left chest pain (either heart or lungs not sure which?) but will roll back to one of my sides and it hasn’t been a huge deal. Well, last night I was jolted awake from being on my back with chest pain so sharp I could feel it in both my chest and back as if a knife was through the left side of my chest. I sat up and breathed through the pain that lasted a couple minutes then went away. Has anyone else experienced this? Is it something I should be alarmed about or just a normal pregnancy symptom? I see my doctor next Tuesday and plan to ask her about it then. I don’t intentionally sleep on my back, and I use pillows all around me to try to prevent it, but I still manage to roll onto my back while sleeping.