I have had some form of PN for about 3 years, and I too experience some alarmingly wierd "inappropriate" smells, that seem to have no tangible origin. However, I tend to view this and most other current medical issues I have as being connected to the brutal effects of treatment with Interferon for HCV.
The thought of 'brain lesion' had crossed my mind at one point, but hesitated to bring that issue up with my DR. at the moment, since I have a real "laundry list" of post HCV tx health issues that I have bombarded my doc with.
In recent times, the abnormal smell experiences have lessened for me, and seem at a normal level. However, I now have noticed my hearing has become real sensative to low, faint sounds. This is new in my life, as I've historically viewed my hearing to be damaged, particularly in the low frequencies.

With all the odd twists and turns, I'm starting to question the need for taking life so seriously anymore.