What Causes Stomach Cramps?

My husband, age 82, slender and active just told me he s been having what he calls cramps in his stomach which started yesterday, went on through the night and has gone on most of today. He s tried to keep working through these pains. Right now, lying down after dinner, he says he feels better than he has all day. He has eaten quite normally yesterday and today and had a normal bowel movement midday today. Unlike what I call a cramp he hasn t been able to stretch it out and make it go away. He s worked in and out of the garage today doing light things, but says he came in a laid down for awhile because of the pain. We drove around in the car today to appointments and to a couple of stores. He and I have been eating the same foods. I have what the doc told me yesterday is paravirus that is in my larynix so I can t talk real well. I m wondering if this could be something serious. Any suggestions?