Mechanic left rear drum too tight!

[warriorpoet]

Hey guys! I'm very new to motorcyles but im fairly mechanicly inclined. I dropped my bike off at the shop to get some new tires. I got it back and it ran great...super smooth wonderful ride. I noticed on my way home that it was hard to move the bike when it was in neutral. That little voice in my head told me to check it out but i ignored it. It would move but it wasnt near as easy as when i first got my bike. I drove it home and then drove it to work this morning....on my way to work i noticed a significant loss of power and smelled that wonderful burning smell. So i pulled over and my rear brake was smoking. I loosened the nut to release the tension and drove the rest of the way to work. The bike works fine but now the ride isnt as smooth. Any ideas what could be wrong? do i need a new drum brake?