My Irish Setter is in unexplainable pain! Please help me!?

I just came home and found my 2 year old Irish Setter laying on the bathroom floor twitching, muscles contracting and unwilling to get up or vocalize. This is EXTREMELY unlike my dog to not be "all over" me once I open the door. I don't know what's wrong with him! The contractions seem to be along the torso, shoulders, flanks, hips, back, and such areas. He is sensative to the lightest of touches and all I can think to do is sit on the bathroom floor with him to keep him company as I look for a solution. My mother has already given him asprin and it isn't helping. What is happening to my baby?