Next time try roasting fennel seeds, grind them and use a forth of a teaspoon, to make a cup of tea. By the way try mixing baking soda and vinegar together. Unfortunately it's no wonder you had that reaction. P.s. Vinegar is mainly an acetic acid.

This seems obvious, but you didn't use the kind with aluminum, did you?

Did you wait until the soda had dissolved into the water and the bubbles subsided? If not - have you ever seen that kids experiment where they soda to make a volcano? You just did that in your stomach.

Perhaps a medication wouldn't be a bad idea

I'm no doctor but I've been dealing with acid reflux all my life and Gaviscon seems to work well for me

Along with my reflux I am a frequent vomiter. However, warm water and laying at an incline really helps.

Lmao do them research before..

I have GERD so I know the feels :(

Saliva can neutralise acid in the oesophagus - try sucking your thumb (or a lolly or something) and swallowing the saliva. While you sleep your mouth produces less saliva and because you're generally lying down when you sleep the acid can travel back up your oesophagus. Use Quick Eze or Gaviscon or any antacid if you have access to them, and try to avoid lying down. I used to have a lot of trouble with reflux and started avoiding foods with lots of herbs & spices (garlic, onion, pepper, chilli, etc) and that seemed to stop the problem from occurring as often. Also if you're eating big meals try smaller meals. Definitely never heard of the baking soda idea before. Hope you feel better soon, OP!

Might be an interesting projectile mixed with green coloring. Exorcist style!