Hi Emily - I was just reading about Fifth Disease and it sounds a lot like Lupus - and a lot like what you've been suffering. Both cause basically the same symptoms.
About the only way you can tell them apart is with the lab work.
I hope you get to the bottom of what's causing you all these different symptoms! Wow! Arthritis-type pain, fatigue, headaches, etc. Please take care of yourself and when possible see a doctor.
Wishing you the best
I would suggest you make an appointment to get this checked out.
It may possibly be a problem stemming from your cervical area (neck) or from a carpal tunnel problem. The doctor may check your arm and wrist, send you for an xray or ultrasound scan and also a nerve conduction test to confirm whether or not you do have compression of nerves in the carpal tunnel.
If you use your left arm/hand a lot, it could be as a result of repetitive use.
You may be advised to rest the arm and hand and wear a metal support over the hand and wrist until it has healed. If you continue to use the hand and not rest it, the condition can get much worse.
Best wishes.
Another possibility is a pinched nerve in your neck. You might want to see a chiropractor or osteopath. Both do manipulation. The advantage of an osteopath is he is also a physician and can prescribe meds if necessary.
Please see you doctor and get checked for ANA and Lupus. My daughter has Lupus and lots of trouble with her hands - wrists. Pain and weakness.