I've recently been diagnosed with RA, and had two steroid injections, been taking hydroxychloroquine for 3 weeks, and Methotrexate for 1 week.
This all started with shoulder joint pains, and then spread to all other joints, but as little as four weeks ago, I was able to walk quite long distances, could garden, and played bowls regularly.
My leg muscles started to ache when I went uphill, and fairly soon (three weeks ago, just before my diagnosis) began to ache even on the flat.
My joint pains and swelling have got better, I assume because of the two steroid injections, but my muscle pains have got worse. Even after a short stroll, my legs feel as though I have run a marathon. Going upstairs is a "to be avoided" activity. I also get similar effects in my arms when getting dressed, and even more strange is my jaw, where I need to take constant breaks when chewing.
I have read suggestions of loss of muscle tone, but I am inclined to not think it's that because of the short time it has taken to occur, and if anything, just feeling my muscles, I think they are as toned as they ever were.
I am even sleeping well, (maybe too much even) although rolling onto either side in the night can develop a shoulder ache.
Hearing any suggestions or similar experiences would be helpful as I seen to read very little that seem to match how I feel. I guess that's one of the vagaries of the condition though.