Why do my eyes hurt after I put on contacts? Am I doing something wrong?

Possible misfit. If your eyes hurt after placing contacts on it could be that they have been misfit for the shape of your cornea. This is especially likely if the eyes hurt immediately after placing them on and they keep hurting. If the eyes are initially comfortable and then hurt later on, it could be that you have dry eyes and your lenses are not permitting enough oxygen to get to the cornea. Tears might help.