1993 Mercury Sable my brakes continue to be a problem

I am a relatively new driver who picked up a car for cheap before I even had my permit. I had everything checked out and everything was fine except for this weird clinking noise coming from what seemed to be my brakes. I ignored it for a while and mentioned it to my mechanic whenever my car went for checkups however it wasn't until the past few months that things starte to go downhill. When looking over my car in an autobody class I found that my right rear caliper was seized up and needed to be replaced. Then after waiting about a month the screeching started to get to me and I supposedly had my car competely fixed. But now ever since then my cars brakelight has been coming on and the "clunking has worsened. And the check engine light that I failed to mention before has been coming on more frequently. Then tonight I thought it would be good idea to put my e brake on and released it as a last attempt and now my car is accelerating very slowly and my car smells of burning rubber. WHAT CAN I DO? Please help
-steven