Why do I have so much arthritis pain?

Need information. It depends. I cannot say without more information. Many people are susceptible to developing osteoarthritis (wear and tear) at an early age. Genetics definitely plays a part, in my experience often associated with one's mother's degree of arthritis. There are autoimmune causes of arthritis such as lupus, rheumatoid and psoriatic arthritis. Start with your family doctor for evaluation.
Interesting question. Im not sure if at 22 you really have "arthritis pain"/ if your symptoms continue and limit your activities you should be evaluated by either an orthopedist or a rheumatologist there are juvenile types of arthritis but im not sure if you have that - you need to be thoroughly evaluated to get that diagnosis.