I have constant pain in every joint, from my head to my toes. I lose my balance all the time. I am very tired to the point I could fall asleep standing up. I've had restless leg syndrome all my life (sometimes a prelude to MS). An MRI was clear. But I haven't been able to walk very well since last week. My ankles and heels are very stiff and extremely painful. I can only hobble around. After 3 days of this I went to the hospital to see if I had somehow twisted my feet. They took x-rays, no damage, blood work, no inflamation, everything came back good. But I still can barely walk. My nuerologist said I have Firbomyalgia, but I didn't think it effect walking. I've not yet had a spinal tap. Could these symptoms really be MS, even with a clear MRI?
Sore, stiff ankles -- MS? Yes and no. MS can cause stiffness in joints. That is why physical therapy is important. However, there are other diseases and conditions that cause stiff joints, too.
Your doctor can answer this better than I can, but be aware that an MS diagnosis may take a long time. The diagnosis process may also lead in another direction. Good luck finding the answer.
Ask your doctor to check your vitamin D levels. Low vitamin D results in muscle and joint stiffness and pain. I was having a lot of trouble walking, and my neurologist added 50000 iu of vitamin D once a week to my meds for 4 months. After a few weeks I was walking without any pain. Now I take it every other week to maintain my vitamin D levels.