Why do i feel a cold feeling on my wrist and under between their and my elbow?what tests should be done ,doctor?

Nerve problem: There are a variety of causes from a nerve issue to an issue of the elbow or wrist joint itself to an overuse syndrome to other medical disorders presenting with limb symptoms. Deciding whether a test will be helpful or not in this case involves some sort of examination to decide what the likely diagnosis is (depending on this may be blood tests, X-ray, nerve conduction tests). See Dr for exam.