My son had colic. The first six months were crazy. I made a CD of filled with the sounds of vacuum cleaners and hair dryers because it was one of the only things that calmed him down. Sometimes I would just put him a car seat and just drive. When he was old enough to "appreciate" the electric rocker-damn I must have celebrated that day when it finally worked.
If it's a stomach bug, ugh! My mom used to get a hot water bottle and put it over my tummy (after wrapping it in towels so I wouldn't get burnt). Sometimes that would help. And sometimes it didn't - but I appreciated the effort.