TMI/Semi-Embarrassing Question

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Anybody else get digestive distress while/just after finishing a workout? I've started to have this problem when I run, & I'm wondering if it's a diet thing, or something else.

It usually happens the day after I eat out... like today. Yesterday, I had a side-dish of chip truck fries with my chicken breast & garden salad at dinner... (maybe 300 cals of crap) my family ate chicken fingers & poutine. I thought, you know, portion control... stay within my calories...

Is this because of the running, or is it an issue of my body rejecting junk? Because if I eat the junk & DON'T run, I don't have this problem. If I don't eat junk the day before running, I don't have this problem. It's when I do both together that it seems to happen... the stop-the-treadmill-run-to-the-restroom-in-the-middle-of-my-workout issue, that is. I don't want to deprive myself of foods I enjoy because I feel that sabotages success & causes binges. But is my tiny-portion giving me stomach problems?