What can cause a sharp pain either in my chest or right below it?

I’m 22. I’ve been constipated for several years, and I’m going but I feel like there’s stool that I can’t get out. Since around summer or fall last year, I’ve been having a feeling of fullness right under my chest. In September 2024, I also felt like I started having chest pain or pain right below my chest that would radiate to my back. It gets better at times and I don’t really notice it, but other times I feel like something’s wrong. Today I was exercising, and not too long afterwards, maybe 30-60 minutes, I started having a sharp pain either in my chest or right below it, and it’s radiated to my back at times. I felt tired today too, and like I want to go into a deep sleep but if I rested I don’t know if I’d go into a deep sleep. What could be causing this feeling, and could it be something serious?