Pulled muscle or more serious?

So earlier this evening I cam home and was changing clothes and I felt like I moved wrong when I took off my bra. Like an hour later I had this horrible pain under my breasts, and along my shoulders and lower back. Like an intense pain that I couldn't get comfortable in for about five minutes. I tried gently stretching and that seemed to do little. I finally just ended up waiting it out and all was hunky dory with a little residual pain under my boobs. I did just start a stretching video to increase flexibility so maybe this triggered something I did wrong?
Pulled muscle or more serious?
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