I Have Been Having Stomach Pains And Severe Head Aches

I have been having stomach pains and severe head aches for a month now. Have only been able to eat rice, toast, and bland foods during this time. Can feel my pulse heavy in my upper stomach area along with pressure and pain, especially after eating. Today I was drinking water, felt sick, and vomited. A clot of blood about the size of a golf ball along with a couple of veins attached to it came up along with regular stomach fluids. After dry-heeving a couple times, just a little bit of blood came up, then after a few more sips of water, it was just the water I frank coming up. No Blood. My stomach feels 50% better after a couple hours. My question is.....What was it? What could have caused this to happen? What should I do now? Thanks