Maxima23

All - I apologize if this subject has been previously posted somewhere or has an obvious solution, but I'm short on patience and time right now so please bare with me.

Yesterday my Maxima started making a weird wobbling noise all of a sudden while driving, coming from the front driver side wheel. It continued consistently while driving. I got out and looked and couldn't find anything wrong, but suspected a broken bead in the tire so I took it by a tire shop on the way home. A guy there said it seemed to him like a busted bead and that he could feel the bulge. When I got home I felt for the bulge and couldn't feel anything, granted I don't have experience in that area. When I pulled the wheel off to get a better look I noticed the wheel axle nut was loose. I tightened it down, drove the car, and didn't hear anything, but about 20 miles later it started again, only this time it only happened under acceleration. I pulled the wheel off again, but the nut was still nice and tight (I did also replace the cotter pin). I rotated the tires and again, no noise - so far.

Does anyone know what this could be? I'm thinking brakes somehow? Slipped pad maybe? Another note, about 2 weeks before this happened, I started getting that metal scraping noise (from this same wheel) you get when your pads need changing, but then it stopped several days before this incident. Thanks in advance for any input.