I keep getting a weird tightening/spasming sensation in my lower chest, mainly under my breasts but also centrally between them. It seems come on when taking deep breaths, leaning forward or lifting things. I did some exercises yesterday for the first time in a while, could I have just strained something? It doesn't feel like a pulled muscle as it's more of a sporadic tightening. I do have reflux and hiatus hernia so could also be to do with that but unsure as it's a new sensation. It's freaking me out a bit! Has anyone had similar? I've got a gp appointment tomorrow afternoon but may go to out of hours later if it gets worse.