I can relate, I've been there & done that and I'm still undiagnosed too. I have had colonoscopy & endoscopy (both with biopsies), CT scan, many blood & stool tests, etc... and they all came back totally normal. Fortunately I have a decent GI, who knows that my pain is real and that there is something serious going on with me, we just need to find out what. Sometimes every test will come back normal and it's so frustrating. But I'm not giving up, even though it's hard not to mention expensive, I need answers and I know I can't live like this forever. I'm having a pill cam done in a few weeks, and if that doesn't give me answers, I'll fight to have another kind of test done.
My advice is to not give up, you know you can't go on like this forever, being miserable a lot of the time. You need answers and appopriate treatment, and you have to fight for it and become your own best advocate. Call your doctors, ask what the next step is, pursue further testing, ask what medications would be appropriate, etc. I know it's so frustrating and incredibly depressing when you're in tons of pain and having many symptoms, and the tests say you're fine. You know that something is wrong, and you have to get answers for yourself and your family's sanity. If your doctors give you the brush off or say that you're crazy/depressed/have IBS/it's all in your head, find better doctors and get second opinions. You can do it, you just have to keep fighting, even if it's easier to give up.