Ask a Neurologist and Get an Answer ASAP
If you are having cramping into both thighs -- this isn't a result of your stroke.
I would ask your family doctor for evaluation of the lower back -- lumbar spine -- with MRI lumbar spine.
This is to rule out conditions like lumbar stenosis:
which can cause cramping in the legs, worsening with exercise.
(If it were somehow related to your stroke, cramping/tightness in the muscles would only affect the left side).
I sincerely ***** ***** I have helped you, and that I have earned my 5 star rating today! Please remember to rate my service by selecting the 5 stars at the top of the screen ( rating me now does not close your question). We can continue here until you are satisfied, simply use the reply box and let me know. Thank you!
Because your symptoms seem to start 3 1/2 years after the stroke, I would want to make sure that your doctor has ruled out other issues that could cause increased spasticity, and so if they have ordered MRI of the lumbar spine, also checking the rest of the spinal cord is recommended.
Then working with a physical therapist would be best -- and yes, strengthening and stretching of the affected muscles would be very helpful, as it seems to be exercise related.