To get the camera to follow your main character again, you can double click on their portrait. Unless you are talking about another issue with it.
For me its just every where, the underdark, the surface area, walking and wanting to (for me its natural as a human being ) to look around. Hell I would be happy if I could at least lift my field of vison a few degree above straight forward. I dont need to look straight up above my head.
This is one of the most frustrating parts of the game for me. Especially considering they brag about the verticality of the game, but we are stuck with broken necks and can't look up. Sadly I doubt they will fix this, all we can hope for will be a mod most likely.