Have you tried Pedialtye? That was what was recommended to me when I had lithium toxicity and then kept throwing up for a few weeks after that. The Pedialyte popsicles are good when you are really nauseous because they are big and force you to go slow.

I get very overheated very easily on this med cocktail including feeling sick and so I have a backpack I carry that has iced washcloths in it but it also has a package of tubes of Pedialytel powder that you just dump in a 20 oz bottle of water and shake it up. That helps a lot.

They also have liquids available. I can't remember what those are but I know I used to be stocked with them when my meds were making me throw up.

Might be worth a try?