Question is in the title really...I could be standing up going anything, or laying in bed, and I'll get a stitch in my stomach, but it will be REALLYYY painful to the point where i flinch to hold my stomach. Any ideas?!
EDIT: another thing that could be important to add: whenever I run up some stairs, I get so out of breath that I have to sit down to catch my breath again. I eat healthy, have a healthy bodyweight and do a lot of exercise - this has only recently started happening?