Yeah tell me about
it, I ordered some Alka Seltzer Gold on Amazon and it never came, or it was delayed for weeks, when I needed it very badly that weekend! I had to cancel the order and make my own (minus the potassium)...
Just fresh squeezed lemon (1) and baking soda (tsp) will give you a very similar fizzy drink, that could settle your stomach and more hopefully.
https://www.neuroborreliosis.com