I have a d3100; when using my Tamron 90mm f2.8 lens (~8 months old), lately I've noticed a black fuzz in the viewfinder and in images that contain a lot of white. I've used the in-camera "auto" image sensor cleaner; that doesn't get rid of the fuzz. I don't notice the fuzz when using my other lenses. Any suggestions on how to clean the lens and/or body myself? Or should I have it professionally cleaned? Thanks!