I bought some excellent multivitamins in capsule form (powdered in a gelatin capsule) that dissolve completely within minutes of consumption...there are different formulations to choose from, so you should be able to get one that suits your needs. These are from the Vitamin Shoppe, and if I recall properly, they are online, the URL being http://www.VitaminShoppe.com
(I'm not advertising for them of course, because you can get similar products at health food stores, but I've found the proces to be better at this place. The disadvantage is that you have to wait for the delivery rather than instant gratification at a store.)
I wish you luck, and no more kidney stones! Those little buggers are some of the most painful things anyone can experience.