Can anyone suggest ways to manage this condition? I have suffered repeated severe and painful sickness attacks since I was 15 and no medication seems to help. The doctors don’t seem to know much about it and I really feel as though I’m not getting any help.

It’s taken me years to figure out mine is from Acute Intermittent Porphyria and migraines. I focus on avoiding triggers, I use Stemetil which calms the nausea, and have a recovery plan which includes grazing on sweet rice pudding (high carb is the remedy for AIP). Not much help for you. Journal your symptoms and look for patterns, triggers, and do lots of research.