Welcome to the CP board of HW! This is a great place to come to receive and give support as well as experiences. We are a very close knit group, and love to have new members (although we always are sad to see another person in pain) While none of us are doctors, together, we have a great wealth of knowledge from our shared experiences with pain of all types. However, our experiences & advice should never replace that of a doctor. That being said, on to your questions, etc.
First, let me say that I am so, so sorry that your arthritis medication caused MS & lupus. Besides having to deal with the pain & disabilities associated with arthritis, just one of those conditions would be devastating, but two?! Wow. MS is something that is still "on the table" for me (although currently it is lower down on the list). I know how terrified I was, even to have MS suggested! There are both MS & lupus boards here on HW (as well as arthritis) & you may want to check them out as well as they can probably give you some better 'disease-specific advice!'
As for pain management. There have been many threads about pain management & pain management physicians, etc in the past. You may want to search through some of these -- just hit the search button in the control panel & type in a key word, such as pain management. We often use the abbreviation "PM" to mean pain management, pain management clinic, pain management program, clinic, etc, as fits with the context. Most of us here are patients at PM clinics, although for some of us (me included), another doc, such as our "pcp" (primary care physician) or neurosurgeon has taken charge of our PM.
Your doctors may have already told you that many, if not most PM clinics only accept new patients with a referral (this was the case with mine, during the time in which I was a patient at a PM clinic). Ideally, you want to see a PM physician who is board certified in pain medicine. Often times, these are anesthesiologists or neurologists that have continued their training to specialize or become board certified in PM. Some practices also employ nurse practitioners & physician assistants, who you may see once you have established a plan with your PM doctor. That being said, not all PM clinics are equal. Some only do pain relieving procedures (injections, nerve blocks, etc), whereas other do both procedures AND prescribe medication. Ideally you want a clinic that does both. Different medications are used for pain, and likely, you will be put on a combination of medication. Examples of classes of medications used in pain management are anti-depressants (such as cymbalta and amitriptylene/elavil) - these anti-depressants are known to reduce nerve pain, anti-seizure medication (such as gabapentin/neurontin and lyrica) is also commonly used to treat nerve pain, muscle relaxants (such as zanaflex, which in addition to helping musclar pain, is also known reduce the amount of pain signals received by the brain), and opioids (your "traditional" pain medication, such as morphine & oxycodone). If you are prescribed an opioid medication, you are generally required to sign a "pain contract." The details of which vary slightly from PM to PM, but these contracts basically state the "rules" which you must follow in order to take this medication. Depression & sleep problems are very common with CP, so your PM may start you on medication for this as well.
Generally, before PM's resort to long term opioid use, they first exhaust all other options, including other medications & non-invasive procedures. At the time in which you are placed on opioids, depending on the nature of your pain, you may be prescribed both a long acting medication, and a short acting medication for "break through" pain.
I think this covers just about everything, but I'm sure others will be by to welcome you & add some more thoughts! Good luck & keep posting with us!