Black tounge is not a manifestation of blood shortage.
Most common causes are poor oral hygine
Tobacco use
Excessive antibiotics uses
Dry mouth
Excessive alcohol use
Kindly share a picture of your tounge for further guidance and management.
Is there any increase sensitivity to sour and spicy food or recurrent burning sensation in mouth
Next Steps
For further clarification, complete evaluation, correct diagnosis and treatment and prescription feel free to consult me on this PRACTO APP. Stay safe and take care of yourself