You need to see your rheumatologist for an examination and a definite diagnosis. But without seeing you, your symptoms sound like sciatica, a pinched nerve at the spine, possibly from a herniated disk that worsens when you bend forward.
I have RA and I have been on methotrexate for a month with prednisone and NSAID. I have been feeling great for the first week. I went back to my daily 30 minute walks, that I couldn’t do for over a year. I have RA in my hips. But now I have a differnt kind of pain in my hip that goes down the outter side of my leg to my knee. I get the most pain when I bent forward like picking something off the floor. I was wondering If this could be an inflamed tendon or bursitis. I get inflamed tendons all the time in my other jionts. I think I might have sarted walking to long to soon.