serious problems

I recently had my cv's replaced by my home mechanic in maine(used parts, rebuilt), but after i got the car back it had this strange vibration when i was in gear and stopped, and the same vibration at about 2100 rpm and again above 3, it's hard to describe but the best way i can explain it is it feels (at a stop) like it's a diesel (the whole car shakes, doors especially and the little plastic door that covers the cd player) it was annoying at first, but i was due back to florida for school in a few days, so i drove it back with the vibration. well, it seems, the vibration is getting worse. i just got back from a drive to orlando from here in daytona and it sounds like something is grinding or its running rough. my first though was that i was running it out of oil (oh no!) because it leaks a lot, but i checked it and the level was fine. i dont know if it's an engine problem or maybe a transmission mount or whatever, but it wasnt there before i got the cv's replaced, and it's getting worse. anyone have any ideas what might be the problem? and if it's something serious, is there anyone who can tell me where to take it down here to get it fixed?

thanks,
mike