I need some help. My bathroom on the 2nd floor has very little hot water pressure in the sink and shower... I cleaned out the screens and had my hot water heater flushed... any ideas?

All your valves open?

I believe they are but I will give a double check... checked valves all are open, any other suggestions?

How old is your house and what material are your water pipes made of? Did the loss of pressure happen all of a sudden or dit it come on gradually? It sounds like some crud got into your valves and you will have to open them up and check the seats and inlet ports on the cartridges an d then flush out the supply lines. Regards, Tom

The bathroom is about 11 years old... it has been happening on and off for a while now.

Do you have a dishwasher &/or washing machine operating when the pressure is lost? It happens to me when the washing machine is filling. I'm in the process of remodeling the master bath & am going to increase the mains to 3/4" to gain more volume.

No, I have nothing else on, when this happens! I have a plumber here now, working on the mess I made with taking off the handle in the tub

In a earlier post I said, "some crud got into your valves and you will have to open them up and check the seats and inlet ports on the cartridges and then flush out the supply lines."
And I'll bet that's exactly what your plumbers going to find.
Cheers, Tom