CIS or MS progression?

Hi there!
I am new to this site and my neurologist is taking a ‘wait & see’ approach. Diagnosed with optic neuritis in March, nothing showed on MRI or spinal. Differential diagnoses is complete. We were hoping this was a one off event (CIS) but have been experiencing extreme fatigue, joint pain and Uhthoff’s symptom in the last couple of months. Could this be my body going through a long healing process or a progression to MS. Any thoughts?