My first thought is that it would be a hernia. That by itself shouldn't cause intense pain, except if your intestine gets squeezed into the rip in the abdominal wall when you have food to digest (which does sound like your meals), then the problem is "intestinal obstruction" (be careful with that, it can also cut off the blood supply to the intestine, IF that's what it is). When you exert yourself, the intestine will have extra pressure on it.
When you lie down on your back, relax your body and your nerves, put your fingers on the area, and gently push the area, you should be able to gently massage or work the intestine back in to it's normal area INSIDE the body and there will be relief. Eat easy to digest, soft foods,...or better yet, avoid solid food all together and drink vegetable juices for superior nutrition without straining your intestine with solid food (no digestion will be necessary, only METABOLISM). If you start right now, you might feel better tonight after bowel movements (the toilet). Not having any solid food in you will also relieve alot of pressure in your abdominal area. I wouldn't even suggest that vegetable juices with live enzymes (fresh) and minerals might repair a hernia, but they might help prevent the situation from getting worse until you can get surgery. It might not even be a hernia and the pain could even be an infection, but I would think it is a hernia.
(minerals are always important. When you get to the site, press CTRL F (control F), enter DIGESTIVE, press enter, the word will be highlighted. Press enter again, and again.
If you're not sure about a mineral deficiency, look at your fingernails.
Garlic is good for the digestion and also cleans the blood.
Digestive enzymes are always good, especially for digesting oils.
SEA Salt is good for everything.
A mineral imbalance can happen if you drink too much water.
With vegetable juice and proper minerals, you will probably feel better, but rule out any infection also.
As far as I know, hernias ALWAYS need surgical repair eventually.