If you otherwise feel well, with no mouth pain or sores, no fever
or chills, and no problems breathing or with your heart, then chances are good that the bluish hue to your tongue is not a serious medical problem. Nevertheless, it is always best to have any new symptom like this medically evaluated, so I suggest that you get in to see your primary care doctor
at your convenience.
Occasionally, bluish discoloration of the tongue can be from something called cyanosis, which is a problem in which the blood is not carrying enough oxygen. Your doctor will be able to examine your heart and lungs closely to make sure that there is no evidence of this serious problem.
Assuming that your doctor is able to rule out cyanosis, then the most common (nonserious) reasons for having a change in the color of your tongue include discoloration from brightly colored foods - for example beets can do this. If you have recently consumed a food that might have the potential to discolor your tongue, all you need to do is wait a few days and the color will disappear. Similarly, sometimes the tongue can become discolored due to growth of bacteria and the accumulation of food debris. You can fix this by brushing the tongue vigorously with your tooth brush and gargling with mouth wash.
Talk to your doctor, who will have more advice for you on how to deal with this problem!