How long have you been fasting? I ask this because my usual fix is to take a shot of apple cider vinegar with a glass of water.
I know it sounds strange to add acid to what you think is to much acid but since you haven’t been eating, your body might not be producing enough acid.
Since I’m not a doctor (and people don’t believe me anyway) I’ll link to a video by Dr. Jason Fung. He starts talking about it a 4:53.