I don't think you should be concerned about being hooked on famotidine. I take it sometimes and don't have acid rebound when I don't take it. One can feel hyper acid at various times for various reasons and doesn't seem to be related to your weaning off nexium. So just manage it with famotidine, and you can take Tums and/or Gaviscon Advance. See what's going on that could cause it to happen now - maybe extra stress, tension. Do relaxation exercises, eat dinner early, etc... No coffee, chocolate, etc...