After a long drive with lots of breaking my girlfriend started to notice a plastic burning smell. A few seconds later I started smelling it. I opened my window and it was even worse, I closed it and turned on the air. When I came to a stop I opened the window again and it smelled so bad like burning plastic that I was getting a headache and my girlfriend felt sick to her stomach. When we got to our destination I looked under the car and tried to smell where it was coming from. I then moved to the driver side front tire and smelled by the break. It seemed like this is where it was coming from. I touched the rim and it instantly burned my hand (not bad). None of my other rims where hot and you could hold your hand on them as long as you wanted. The guy that was following us in the mustang cruise came up to me and said tons of smoke was coming out from around that area. What could be going on with my front drivers side break? I also notice when I come to a stop that I here a grinding sound. I did bring the car to have it checked a few weeks back and they said the breaks where fine.