I have been getting severe pain and cramps in my affected leg especially getting up after sitting for a while.
My parkinson physiotherapist suggested that I hold onto something steady like my kitchen sink or cupboard at similar height and pull myself up to stand on my toes. This was really painful when I first tried it but I persevered trying to get higher on my toes each time and I think it is helping. She also suggested that I do the opposite by then resting on my heels and pulling my toes off the ground.
I don't know whether anyone with a similar problen would find this useful, but it may be worth giving it a try.