Wow, the things we mums have to go through with our babies! You indicated that some tests were done, but not what type or by what type of Dr. There are handy old tricks that do the job, as many have outlined. I would only recommend that you make sure everything is working correctly, and that your child doesn't have any allergies to anything, or any gastrointestinal problems. For that, I would see a pediatric gastroenterologist, ask them to test to make sure no food allergies, or environmental allergies, and that all is working the right way. If so, than rely on all the suggestions so many wonderful mums have made.
My child had severe food allergies....soy, cows milk, environmental allergies too (mountain cedar, mold, dust mites, we live in Texas...pretty much, the entire state). So, there we were using an incredibly expensive formula because I could not produce any milk, my child had acid refulx, was in pain from the allergies irritating his intestinal tract...we had so much fun...he never slept. Once we got the things he was allergic to out of his diet (fruit juice, etc too), and let him detox for a while, and slowly added things one at a time with careful monitoring, well, live has gotten a lot better. When we fed him rice cereal for the first time, he had a solid BM that was bloody. Off we ran to the drs office, no blood in the stool, no blood in the intestine, no one could figure anything out...but no more rice cereal for a while. Our babies systems are so sensitive, making sure the plumbing works right and the input is not irritating are the first steps. Good luck getting sleep and try not to worry. As so many have said, your instincts are valid, don't ignore them.