Pain in achellis tendon

I have had MS for 10 years, and have now started getting a tightening feeling in my right ankle/Achellies tendon and wasn’t sure what to do.i do stretching exercises in the day, I do t wear high heels and in the morning it takes me a while to get down the stairs… Does anyone have any idea as to what I can do…does this mean I am having a different attack and will it get better? I have had steroid injections in them before but at the top of my ankle, this is now a real tighenting at the back of my ankle. Got any suggestions?