I have Ehlers-Danlos (joint hypermobility syndrome--not MS, but certainly causes the same extreme joint pain, fatigue, migraines, etc.) and as a result, am on several medications for pain management, CNS, and muscular issues. I would not be overly concerned about adding Plaquenil to an already extensive medicinal routine. Plaquenil, compared to my other medications, has been very mild in terms of effects and I know it does some good, even if it does not alleviate my pain to the extent that I would like. It reduces my inflammation levels, which makes it worth it to me.
Like you, I also notice that I am strongly effected by some medications; I either have increased joint pain or dizziness, or depression and anxiety.
I still maintain an optimistic outlook because, over time, I have become accustomed to the pain and fatigue and have, to the best of my ability as an active 28 year old, tried to build my life around these "quirks" I have. A pain level of 4 becomes the new 0, and as my pain has increased in the past year, I'm sad (and relieved) to say that a pain level of 6 may be the new 0. It's not an answer I particularly like to remaining optimistic, but it's working for now.
I may soon be looking into other ways to manage the inflammation, but for now, Plaquenil seems a good bet, with very few emotional or physical side effects. It can be hard when you have two separate conditions that have medical treatments sometimes at odds. Hope this helps.