Awe Purple... this lithium business is giving you a go for your money
I don't have stomach problems from lithium, but both of my teens do, 16 & 18.
My 18 yr old daughter is also lactose intolerant.
We all like Acidophilus pills. There is a good one from whole foods here called YumYumDophilis (sp?) The chewable ones you keep in your fridge work best.
Also, on a side note, I used to eat raw green apple peel for acid reflux while I was pregnant. I don't know if it would work for you, but it's an old wives tale that did work for me.