What are the common causes of joint pain in a 25 year old patient?

Need clarify. There may be different reasons, but we need to know what joints, what makes it better, what makes it worse. Do you note it with specific activity. Are you able to play certain sports and not others? Do you joints swell? An evaluation is necessary to clarify your joint aches.
Many. Pain in the joints in the late teens or 20's always could mean inflammation. Or it can be secondary to previous injury. One oft ignored cause is hypermobilty, or excess laxity of joints. Women are more prone to this than are men.