It is also possible that the biting and licking could break the skin and he could get an infection, which could lead to a more expensive visit to the vet so it is certainly worth getting it checked out sooner rather than later.
It may be that he hasn't been bitten by anything at all and is having an allergic reaction to something else, either in the home or out of it. Have a think about any changes that may have been made recently. For example, have you washed his blanket: He could be allergic to the soap powder or fabric softener; have you used any deodorizing products on your carpets that might cause an allergic reaction?
If you have, then the obvious thing to do is to re-wash the blanket in a powder that is designed for sensitive skin; or just in plain water to try and get rid of the other one; and to vacuum your carpet thoroughly to try and get rid of the deodorizer.
If the allergy could have been caused by something outside, think about where your dog has been recently. Have you taken him on a walk that has plants that he is not familiar with; or could he have had any contact with wildlife like toads?