Took out my old fiberglass stall shower and had a tile shower built had it for a few months now and no problem. Had the dam built up to 16" so if I wanted to I could put a plug in the drain and fill it with water for soaking... Now that I've torn out my other bathtub from my other bathroom (they are back to back) to put in a whirlpool tub... and I started using my "shower" to soak in at nite (I have a very physically job) we have realized that the "new" tiled shower is leaking, most likely through the grout into bathroom #2... so now can I just reseal the tiled shower?? Or do I have to re-grout it?? Or is there an other product to put over the grout to seal it better? I'm trying to do as much of this as I can as I can not afford a full fledged Pluming Contractor... Help?!

Grout never holds water. The pan material is used to waterproof. If you did not use pan material or if it leaks [which it is] the bottom 26 inches will have to be redone.