So about 1 1/2 ago I was told my right rear wheel bearing need to be replaced which I did and just a few months ago this mechanic shop told me i needed to repace it again. Would thiscause my right rear tire to wear out so quick? I just put a new tire on around the same time I replaced the bearing. The left side is still good, so I'm lost...

 

It's possible. Depends on how the bearing failed and if there was movement in the hub and if it caused the alignment to change. For me personally, i had 3 bearings fail, and not one caused any tire wear issues.

I'd recommend getting an alignment after the bearing is replaced to check this

 

That also is strange because I just got the alignment done after new tires installed and camber kit installed, and the wear is right down the center it did that to the last tire I had on.

 

If the wear is not on the sides but in the center your tire was most probably overinflated.

 

What he said. Wear down the center usually indicated overinflated tires.

What pressure are you running and what tire size (if not OEM)

 

Post some pix if you can. They will help better ID the issue.

 

You can't always trust tire installers or alignment mechanics to inflate your tires correctly plus the gauges can be incorrect. Tires wearing out the center indicates they had the maximum pressure in that tire, somewhere around 50 psi. Tires have written on their sidewalls max pressure and some dummy's think that's what you should run...not! Tire pressure in our tires s/b between 35 and 37 psi, nothing more or less! Your wheel bearing issue is another question? Make sure you're getting a real Nissan part not a part from the local auto parts store! They should last 100K+ miles, I've never replaced them on any of my Nissan's going back to '72.
Gary