Severe Abdominal Attacks - HELP!

My husband is 24 y/o and is very healthy, very active/fit, however he gets these Severe abdominal attacks every so often with no reason or warning. They first start off like a bad stomach ache and he heads straight for the bathroom thinking it is just an upset stomach. Within minutes he is experiencing diarrhea and SEVERE abdominal pain. The pain is below his ribcage and above his belly button, directly in the center. The only way to discribe this is as an attack. He explains the pain as feeling like a knife is stabbing him and being turned in his stomach. The abdominal pain is so intense he becomes lethargic and completely out of it. He doesn't respond to anything and begins to slur his words a mumble. Within mintues, his hands and feet go completely numb and his hands begin to cramp up and curl in. At this point he is trying to tell me to call 911 or get to the hospital (Although I have already done this, but he doesn't process me telling him so). After a few minutes he is vomiting from the intensity of the pain. He says there is no nausea before or during the attack, but the pain is so severe he vomits. My husband has an extremely high threshold for pain, so this attack is so confusing to me. The entire attack usually lasts around 30min give or take. This means by the time we get to the hospital or the ambulance gets here (we live out of the way) the pain/attack is over. Once the attack has subsided, my husband feels nothing besides some mild (5/10) stomach pain. And he feels like he did before the attack, like he could run a mile. So the doctors look at him like he has a 'belly ache' and send him home. This is very frustrating because nothing has been diagnosed or been given to help. We are seeing a second Gastroenterologist next week in hopes of a diagnosis. Typically the attacks will happen every so often, about every few months or so. However, lately they have been weeks apart. He said he felt pain similar to this occasionally growing up and one time before I met him so it seems they are beginning to happen more often. We are continuing to seek medical attention, however I would love more advice or opinions. PLEASE HELP!     thanks

[Cdngal]

Has he had any Ultrasounds, CT, to start and then maybe a HIDA scan for gallbladder?

[loveamiracle]

He has had ultrasounds done, which ruled out ulcers and gallbladder as we were told. Our internal doctor said everything looked fine and thats why she refered him to a GI specialist because she couldn't figure anything out. I just don't know what it could be?? Thanks