M.B.
I had this same problem VERY early in my pregnancy. I would get severe heartburn from everything even ice water. I took Tums and Zantac per my OB, but neither one worked. I ended up going on a prescription for Protonix. It helped tremendously. I was only on it for a few months and then it went away on it's own. I am starting to have some problems again, but I am 8 months pregnant, so hey, it goes with the territory!
I hope you get some relief. Some people hear heartburn and blow it off. They don't realize how bad it really can be.