@Moldova - I know what you mean, I have had food poisoning before and it was awful. I wanted to add that I sometimes get back muscle cramps when I run if I maintain the wrong posture.
I have a tendency of leaning forward when I run which hurts my hips and lower back and I usually feel it later on when I get ready for bed.
I am usually fine until I go to bed at night. I usually have my husband apply a little bit of muscle rub to my lower back area. The heat from the topical medication helps to numb the pain and lets me sleep. I usually try to stay off my feet for a few days until it resolves itself.
Sometimes I overdo it a little and try to run faster to beat my previous time and forget about my form. There are times when I get upper back cramps too, but that usually happens when I use dumbbells and lift weight that is too heavy for me and it throws off my form.
That is a really uncomfortable feeling too because you can't get into a position to rest comfortably because it hurts from all angles.