Why am i randomly getting hives on my arms &neck?at first i thought it was new clothes that weren't washed but wore a jacket i had for awhile n got it

Possible Urticaria : Clothing may trigger dermatographism randomly, depending on the amount of pressure clothes put on the skin. This can be a regular phenomenon with chronic hives of unknown cause. Be sure it is not contact dermatitis. See an allergist or dermatologist who can identify and treat potential causes, though be prepared to learn causes are not always found.

Often unknown: Cause for hives is often difficult to establish but if they only involve the exposed areas of the body, then I will focus on agents in contact with that parts of the body or a sun sensitivity. If you have blister-like lesions, then they may be a manifestation of Celiac disease. If antihistamine does not work and the lesions last more than a day leaving a residual lesion, consult a dermatologist.

See a dermatologist: You must begin with a diagnosis. Maybe "hives", as you say, maybe something else. There are various kinds of hives, mostly not allergy. Dermographism, for example.