Lower stomach hurts from coughing ?

I'm a 14 years old girl and I've been sick the past couple of days with a stuffy nose, and head cold symptoms. I've also had a slight cough, and it's day 3 and my lower stomach and my rib cage hurts when I cough. All day during cl the past two days I've sat there slouching while I cough, and I think that sitting in that position while I coughed may be causing this. When I got in the shower my lower stomach, like right above my privates, was a little puffy to the touch. It only hurts when I cough, not when I'm sitting, lying or standing or anything. Just when I'm coughing. And please dont suggest I might be pregnant or have an ovarian cyst or appendicitis or whatever, because I am not pregnant and I doesnt hurt to lie down or walk, but only when I cough. Has that ever happened to any of you? Please help me out, I'm worried this is something rare and dangerous.