I to am on Humira, and have been since May 5, 2008. I have started to have joint pain in my hands and upper arms which occurs the day after my shot. I am going to my GI next week, as this could be Humira induced lupus. I experienced the same thing with Remicade, and it got progressively worse with each treatment. It will evenually go away (for me 1 1/2 years). The only thing that helped was prednisone and MTX. It might not hurt to keep track of your symptoms on a calender to show your Dr..
Good Luck to you, and I wish you well.