hii.. congratulations on your pregnancy. i have gone through your query and allow me to say I understand your concern. From what i understand, bleeding from mouth at this point of time may due to two reasons, one being your excessive vomiting. sometimes continuous vomiting might cause mild tears in your oesophagus due to which light bleeding may occur which might be seen coming through mouth.this is nothing to worry about as it subsides on its own. second reason is due to altered bleeding time of your blood during pregancy. please remember that pregnancy as such is physiological stressfull condition. due to this stress, there might be some disturbances in blood and its coagulation. this is also nothing to worry about as it subsides as soon as deliver. i suggest you to wait and watch and if there is another episode of bleeding from mouth consult your obstetrician. hope my answer helped. have a good health and goodluck.