I work in a local ER, It sounds like blood, if you could take a small amount in they will check you in and hemcult it , that means check it for blood , they will also draw blood work. It sounds like old blood , but do not take the chance, they might want to pass a NG tube,have them talk to your doctor first, you dont want more damage that might be caused by the tube
my thoughts are with you, keep us updated, thanks