Hello, thanks for the query.
Saliva with or without blood.
Possibly there are many reasons but few off them are.
or glossitis (tongue infection)
3 Pyorroea (dental)
4 Bleeding disorder
5 On previous night some hard food ( bone etc ) might causes local injury.
6Pharynigitis or tonsilitis
So please consult a doctor and get blood tests done and find out the cause and take treatment .
Have a good recovery. Dr. HET