OK, it appears that I didn't do this very well. I just tore out and rebuilt my bathroom. The new tub was level when I installed it, or so I thought. I have now tiled all around it....floor, walls, etc. I find that it is now no longer level, tilting slightly down toward the right side of the tub, which is the wall with the showerhead. Water that lands on the lip at that end of the tub pools by the wall rather than draining into the tub. I can't fix the tub level without tearing out a whole lot of stuff. Is thee some other option...something I could put on that lip to allow the water to flow back into the tub? Help!
Take the trim ring off from the handle. The big round one. Run the shower and look inside the hole for dripping water. Slide the trim ring away from the wall on the shower arm and look inside there with the shower running. Make the hole bigger if you have to but not so big the trim won't cover it. If it only leaks when the shower is running I think it is either leaking from the shower or galvanized pipes or head somewhere or in the riser going up the wall to the shower head or from the top of the shower valve. If the tub spout isn't on right it could be blowing back from there when the shower runs but if the water comes from up high I doubt this is it.