Sudden hand and shoulder issues

I have had osteoarthritis in knees for over 20 years and slight issues with hands and shoulders due to so many years using crutches.
But this year in August my hands and shoulders totally seized up and for 6 weeks I could barely do anything and the pain was evil.
I was referred to rheumatology and given steroids for 4 weeks and now the stiffness is only evening through to morning and not so bad but the doc has now prescribed Methotrexate 15mg and folic acid every day.
No family history, so it's very odd.
It also feels not just joints but the tendons feeling stiff.