Thanks for posting on HCM,
Blood in saliva or sputum might come from your gums or lungs. If gums then you might be suffering from a gingival diseases probably an infection but if lungs then it might be something serious such as a lung diseases (lung infection/pneumonia
, pulmonary TB, tumor/cancer etc).
In any case, you will need to see your doctor as soon as possible and well as you mentioned, you will be seeing tomorrow which is good.
Hope this helps