Straight ot the point, threw up sunday and problems started?

Friday and Saturday, stomach was unhappy so I took a hot bath to sweat it out sunday but I end up throwing up huge in the tub. (Color dark brown and food chunks, which I didnt eat anything dark brown), slept rest of day cause couldn't sleep friday or saturday. Then lower back pain and neck pain started. Hugh headache last night with little to eat all week (not that hungry) and everytime I do eat or drink, small cramp or pain occurs (not long though) and now, didnt eat anything and stomach is not happy, feeling weird and puffy alittle. What do u think it is.