Baby long term vomiting

[Victoria2002]

Toddler long term vomiting?
My 15m old has always vomited on average once every 24/48hrs. At the moment he usually vomits in bed at night after being asleep about 2hrs. The GP said maybe reflux so gave us gaviscon with every meal but it makes no difference.
He occasionally goes a week or 10 days (once 3 weeks) without vomiting at all-I imagine that means it's not an allergy or intolerance?
When he vomits he heaves/vomits a lot till his belly seems empty.
He eats really well and has a good appetite.
He's generally very cheerful.
If he's got a fever or cold or teething he vomits 5/10 times a day.
Any calpol or neurofen he vomits immediately even if I hide it in his food.
Anyone experienced this? Any ideas?
Am waiting for a hospital appointment with a specialist.

[Victoria2002]

Maybe hypersensitive gag reflex?

[elliejjtiny]

My DS3 did this from about 5 weeks old until he was 18 months, several times a day. He also had mild physical development delay (sat up at 12 months, walked at 2 years 1 month). Gaviscon, ranitidine and domperidone helped but didn't stop it. Keeping him upright as much as possible helped more. Paediatrician said that his muscles at the top of his stomach were a bit floppy. He is 5 now and is still more prone to vomiting than my others when he has a cold etc.