Lately, I've noticed my oxygen levels are hovering around 97-99 and my pulse rate is about 70-78, but I'm still having this on-and-off breathing issue. It feels like my chest gets heavy, especially in the evenings, and it's been going on for about 10 days now. On top of that, my stomach feels a bit swollen. Could there be something serious going on here, or should I just maybe tweak something in my routine? What do you think?