Discomfort/pain

Under my left breast and above it a little I keep getting gassy like pains and discomfort! It kinda feels like a fullness, and a heart cramp, I've had it bad the last couple days! I'm very gassy and keep burping and all that but it's freaking me out!!! I'm 23 weeks pregnant and this has never happened before! It's pretty constant discomfort, I called my OB and told them what was going on, and they said it could be heartburn? But that kinda doesn't make sence to me! But idk! Anyone else experience this?!? It keeps me up at night! I have terrible anxiety