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It could be just arthritis but I have also seen some abnormal things start out the at way  as well such as scar tissue can invade the joint and put pressure on other bones and cause the same symptoms
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Your thyroid is in your neck it has 2 haves that live on either side of your vocal cords they produce hormones that mainly deal with how your body metabolizes your food is extreme weight lose or weight gain is a common sine along with dull hair, and being lethargic