I am usually using tobacco, khaini, etc.yesterday some amount of blood is coming from my mouth, i can not find out the source.

YOU NEED TO: Find the source! it could be of dental origin such as periodontal (gum) disease or of medical origin such as a growth. This requires a one on one personal and clinical exam. Regardless, stop using tobacco which is a leading cause of oral cancer. It seems harmless now. Many people with untreatable cancers also thought so once.

See your dentist: Could be gingivitis.Or periodontitis..Should get it checked by your dentist..Especially if you are smoking and if are not getting regular cleaning..Can see bleefing..Also can be many more causes..So get xrays and evaluated.