OT - End the urge to vomit
I also have an "immense fear of vomiting" as you do. I have not vomited in 24 years - no exaggeration there - although there certainly have been times I normally would have.
I am just starting Clarkia
and bowel, so I have no direct advice for that. I can, however, state some things to help with nausea/fringe of vomiting. You may already know these.
Ginger - ginger cookies (snaps), ginger ale, dark colas (Coke is fine, sip slowly and let it work), ginger root (found in most grocery stores).
Control the symptom(s) that precedes vomiting - for me, it's nearly uncontrollable swallowing. If I can check that, I check the urge to vomit.
Ice - apply ice to the back of your neck and hold a cube in the palm of each hand (ice in hand applied to the neck + ice in the other hand is fine). You can also apply ice to your forehead and any place a hot flush occurs.
Cool air - sometimes breathing in cool air can help squash the vomiting urge. If it's winter, go outside for a minute. If it's summer, stick your head inside the freezer for a minute. Inhale slowly through your nose and exhale slowly out your mouth.