Yep. I used to have horrible bouts like that, and often they would keep me in the bathroom for up to four or even six hours. Same things. Waves of pain and bloating, sweats, weakness, sometimes passing out for a time. I rarely vomit, but often feel like I'm close to it. Eventually everything would start coming out and I'd slowly start feeling better. Though I always have a slight stomach ache after, and am so weak that I generally have to take a nap or at least lie down.
My sister used to have this too, and we both came up with a nickname for it: "Bargain with God". As kids when either of us had this, we'd sit there in pain, praying, "Please God, just take this away and I promise I'll never do X again, or I'll make sure to do Y better, etc.". Silly I know, but we still use the term now to describe it and no one else knows what we're talking about.
I rarely get bouts that bad anymore, though I still have regular ongoing problems. A few things that helped me over the years: Drink lots and lots of water all day, every day. Always have a water bottle with you when you go out anywhere. Try cutting out all dairy, egg, and citrus from your diet (sucks, I know, but it can often help). Eat lots of fruit and veggies. (If they still cause problems, make sure to cook them first). Whenever possible, replace white starches with whole wheat. Avoid sugar and preservatives. Stick to the "whole foods", basically the stuff you make from scratch at home. Make sure you get some healthy oils in your diet regularly, like olive oil, flax seed oil, or sesame oil. If you like tea, mint tea can be soothing.
I've just started drinking aloe vera juice daily and I think it may be helpful. Too soon to say what the long term benefits will be though.
Anyway, hang in there. You're not alone!