I had problems at one time with showers. It is still not my favorite but it has gotten better.
A thought I have if your husband can help. Is you sit in the bath he can lather your hair and then take a cups of water to wash it out. When my back was in pain I did that to myself.
As for a pool therapy you may want to look in your area cause some will have pool therapy or times for adults only. I could not handle the waves from a child playing.