Shadowfax I get that too. After a bad episode I have to lie down on the bathroom floor for a minute because I don't trust myself to walk and . Then I have to go to my bed because I feel so weak and woozy.
I'd be sure you were getting enough water too. Sometimes that calms my stomach a bit and seems to sort of tell my body that it's over now and I can relax.
Sorry you feel badly, hope you can relax and take it easy for a bit :)
oh, and Good Luck!