What Causes A Lump Of Blood Clot In The Centre Of Roof Of Mouth?

i ate something hot and crispy from the microwave and right after I went to wash out my mouth there was a lump of blood clot gathers in the center of the roof of my mouth. This scares me, the more i nasals at the spot of blood the bigger it got sliding towards back of my throat. I used my thumb and apply pressure on it . It then spew out blood. I did not hurt at the time, just a thin layer of skin funny feeling. That was 3 days ago. I'm now hurting at the back of my throat where the skin strips stopped. Hurts especially in the mornings, have difficulty speaking. Will this heal on its own with antibiotics?