Can anyone help with smoke and burning smell rear of car

[DC1]

Hello all, I was hoping someone might be able to chime in before I go to the shop. Driving home tonight in bumper to bumper local traffic, first time I think I had the heat on since I purchased car. About 45 minutes into my ride and about 5 minutes after turning the headlights on I smell something burning, I thought it was a fire in the hills of LA but I look back and there is a ton of smoke coming form my car. I pull over and the trunk is filled with smoke. I'm not a mechanic but it smells like electrical type smoke. Even someone walking by asked if my car was on fire? So I leave it and walk home. I went back after traffic subsided and drove it home. No warning lights, it starts, idles and it sppears to have all its oil etc. So I let it idle in the garage a bit, when I cranked the heat up I started to smell a faint amonia typye smell? Im trying to figure out if I need to tow it or I can drive it, I wonder if my tailights or something was burning but they all work? Could the amoni smell be antifreeze? Im unsure how to check the coolant im trying to find the manual. If anyone had a similar experience I'd appreciate eany info, its a 2002 with 36,000 miles, I suppose Im hoping it had somethign to do with using the heater for the first time but probably not that lucky? I do have a warranty so its more of an inconvenience but not sure who to bring it to? Thanks so much.