Yesterday morning my dog (my dog is a boxer by the way) was fine running around and playing ball... when i came home at 2:30 in the afternoon she was limping a little but she was still walking around and was happy... now this morning she didnt really want to get up she would stay in one place unless you called her and she would limp to you... now tonight she layed on the couch and wouldnt get up for anything, not even a treat.. she is never like this she is always energetic and loves to play i have felt all of her legs and her back pretty muchly all over and nothing seems to hurt her... what could be the problem?