HELLO, WELCOME TO TO HCM,
as per the details u have mentiones , hives
is not due to depo shot, becoz, if u are allergic to depo shot , u would have get it during the 1st shot itself. so you need to think about some other causes, there are so many causes for hives , some people may be allergic food or some people to any caterpiller bites , mosquito bites and even some times with bathing with a hot water . but as per ur symptoms its most likely CHOLINERGIC URTICARIA
....so we need to investigate properly. i i advise u to see a immunologist.
hope this will help u