dietary changes, any new or increase medications, weight gain/loss, changes to a lower activity level eg sitting more than you use too and effecting circulation, flexibility, muscle strength, spasticity etc,
I also think of things like where exactly the pain is eg knee, upper leg lower leg, hip, etc, if its the whole limb or an isolated muscle thigh, calf etc What type of pain do you feel eg ache, tight, burning, bee sting, spreading, sharp etc and If there is a pattern to the pain eg all the