Hey Upjo,
Chronic pain is draining for all of us on here, but the most important symptom I read from your post is your obvious depression. When you get this down you really need support. Have you spoken to your Doctor about it, are you in Counselling or on anti-depressants?
Your not knowing where the pain is coming from, frustration with Doctors and medication is not good for your mental health, which has a direct bearing on your physical health.
Do whatever you can to change your mindset, you will be better equipped to deal with the present and anything the future may bring.

Dave