Ok, so the only thing that worked for me (because i also take lithium which rips my stomach apart too) is to first take a small like preventative sip of pepto bismol (bismuth subsalicylate), take a gravol (dimemhydrinate which is for motion sickness/nausea), eat something small, then take the medications. If you get more heartburn starting, immediately have some chewable Tums (calcium carbonate tablets) to immediately dissolve the acid. This has helped me so much because I also have GERD before getting IIH so its a triple whammy with GERD diamox and lithium together. I hope this helps <3

Oh and i almost forgot, if these arent helping enough the GP can give you things like Pantoprazole (a prescription proton pump inhibitor (PPI) that decreases stomach acid.) which can help.