Hi: I have a problem with standing water in my tub while showering there is alot of water, could it be my exhaust pipes or gas pipes that could have gotten clogged up that would stop my tub from draining correctly.
It seems that you could have a hair-clog or hardened soap in your p-trap. Call a good drain-cleaner in your area. We charge approx$50.00 to unstop your type of problem.