Yep, it sounds like if your lupus has you laid up in bed, your fibro will act up. It's such a fine line between the two diseases. Its really hard to tell which is causing what that's for sure.
I have the lupus, fibro, and RA, sometimes I can't begin to tell my Rheumy which is bothering. I tried Lyrica and couldn't tolerate it. Both my Rheumy and PCM pushed to try Cymbalta for my fibro pain. I finally relented and started it. I've been on it almost 2 years now I think and it actually does help me somewhat with my muscle burning.
I know it's hard to exercise but with fibro you really need to move or you'll get worse with your fibro. Even if you could manage to just take a gentle walk daily it would be helpful. I used to go to the pool and gently stretch and tread water for exercise. You're weightless in the water so no pain for the joints with your lupus. My lungs however, have become so bad, I require oxygen 24/7 and can no longer go to the public pool. I'm not allowed to have my oxygen by the water.
I know when I was able to go to pulmonary rehab twice a week, it was really helping my fibro. I would walk on a treadmill, ride a stationary bike, lift 4 lb weights and did mild stretching. I hope to return to rehab as soon as my foot has healed from my surgery. So, maybe you could try one of those to see if it helps.
When I started Plaquenil it didn't take the full 6 months for it to work. It can take up to 6 months, but most people respond quicker than that. I hope you start to feel better really soon and remember try to keep moving, eat well, and get plenty of rest.
Hugs,
Barbara