I have pain in my finger. it is turning red and blue.

Needs to be checked: You should get it checked as soon as possible if it is turning red and blue.Most of the time it is caused by trauma to the finger,but if there is no history of trauma.Then it may be due to an infection or impeded circulation for some reason in that finger as long as other fingers are not involved..Raynauds Syndrome will effect all fingers and will only happen if there is exposure to extreme cold

One, many.: which finger is turning red and blue, and what circumstances. if you are a smoker it could be a vascular disease if it is one finger or lung problem if it happen to all the fingers. or it could be a nail problem. your best advice to go and see a doctor.

Blood circulation: There may be a problem with blood circulation to that finger. It could be a problem such as a blood clot blocking a blood vessel, or it could be due to spasms of the vessel. There is a condition called Raynaud's syndrome which can cause painful red and blue fingers but it usually affects all the fingers.In any case, you should have this evaluated to ensure there is nothing serious going on.