recently i started noticing strong exhaust fumes when I turn on my heater. Can somebody point me to where the problem might arise?

Are you sure it's exhaust fumes, and not hot coolant? If it IS exhaust, then you must have an exhaust leak at or near the engine. If the heater core is starting to leak, then you'll get the stink of hot coolant very quickly - but it's usually combined with a windshield that instantly fogs up if you aim the air that way (and won't clear).
Seeing that you have the 2200 in your car, also check that the oil filter isn't leaking. If it does, it drips directly onto the flex pipe in the exhaust, making lots of stinky smoke.
There should be a seal at the top of the firewall that helps prevent air from under the hood from making it up to the air intake for your heater - check to make sure it's not out of place or missing.
Check for those things, and hopefully you'll find the source. You don't want to be breathing more of that stuff than necessary!
John