When points drag strangely that means some of the points are painted incorrectly or connected to the wrong bone. Try finding out exactly where it is then going in and painting over again. Remember you don't want any of the mesh behind it to be painted as well, that's where a lot of errors occur. If you can't figure out the vertices in the end you can send me the file and I can correct it quickly, but it should be pretty easy for you to fix yourself.
Remember as well that some bones paint the same color which can get confusing, so even if something looks painted try just painting over it again to make sure.
Good luck, and I like the Wolf model by the way, it's nicely modeled and textured.
