When I turn on just the hot water in my tub I get very little water coming out. The cold water flows much heavier. I have drained the hot water tank to clear it as problem. What should I do next.

Sounds like you have somr trash in the hot water side of your faucet. Shut the water off to the faucet and open it up. If it's a two or three handle faucet check the seats for blockage and if a single handle faucet check the cartridge inlet ports for debris built up. On both types open up the hot water supply to flush out the supply and the valve body. You don't "drain" your water heater you flush it. Let me show you how. For long life and fewer troubles you should keep your heater clear of mineral build-up by flushing on a regular schedule. Attach a hose to the boiler drain at the bottom of the tank. With the pressure on, open the boiler drain and let it run until the water runs clear. You will see a spurt of red,(rust) followed by white or yellow grains,(lime or calcium carbonate). This shouldn't take more then a few minutes. Do this monthly to keep it clear. Now flush out your hot water lines on ALL fixtures that are affected . Now pull each aerator and clean the screens. Be sure you put them back togather the same way you took them out. Don't forget to flush it out every month. Your heater will thank you for it. Hope this helps, Tom