I been having pain in my arm where I got my depo shot it been a month since I got it is that common?

Yeah, go see your doctor or go to the emergency room if you read this after hours. Read your question. Your sentence is like three partial sentences run together. The doctors will quickly zero in on your issue and tada you will be on your way to recovery. You many be reacting to your drug. You sound confused.

No not at all. The shot I dread the most is a tetanus shot. I find those extremely painful especially a day or two afterwards. Do let your Dr or nurse know. On each side note, the side effect I got from the deposit was gaining 80 ÷ pounds. I liked not getting a period the whole time I was on it but I will take that time of the mmonth over 80 lbs anyday. But please let us know what you find out.

That doesn't sound right. Some injections are thick and cause a little swelling and tenderness for a couple days, but a month is too long. Any injection has the potential to become a sterile abcess . Usually abscesses are associated with wounds in which bacteria was introduced to the wound. Injections are given with a sterile needle and syringe, but occasionally cause and abcess even though there was no dirty wound.
Establish whether the area is red, raised or swollen. Call your Dr. and tell him about it.
Faded time