Our shower pressure has always been great but last week the hot water pressure dropped to a drizzle. This is in the shower only and only with the hot water. About a year ago we had a problem with water leaking in the shower and a plumber came and replaced the knobs. Things were fine until last week. Is there anything I can try to fix this or do I need a plumber? Thanks!

That plumber probably did not replace the knobs but the valves or cartdige under them. Shut off your main supply and open the hot valve or cartridge. If you can give more details so can I. You have small bites of junk in your valve. Flushing the hot water heater twice a year prevents many of these issues, know how to do that?