My dog is throwing up blood?

I came home from school and my dad told me that he had given our 4 year-old dog a suppository for his constipation and that he was having some troubles with his bow movements. he also added that he had been throwing up all day and some of it was bloody. when i got home again later that night i saw that emmett was heaving again and when he through up out came a handful of grass and frothy blood. i consulted my dog care manuel and it said to get veterinary help if things worsened. so i tucked him in last night all nice and comfortable and i hope he slept well. one thing i remembered that my book had also mentioned was that throwing up bile was a bad thing to. now i don't know what that is but just this morning Emmett projected yellow liquid from his mouth then went about like nothing happened ( yall know how dogs are) and now im wondering whether its stomach acid because hes been throwing everything up or yellow bile. what do i do for him? Please help!