Answer:
A lot of possibilties. If you're young most likely isnt heart attack signs but be cautious just in case. Another possibilty is puberty, especially if you're a female. You could also be sore from exercise you could've possibly done. It could also be anxiety but please don't self diagnose. Those are all the possibilties I can think of, but I'm sure theres more.
Step-by-step explanation: