Hi Juli,
first let me say it sounds as if you're just doing too much especially on the walking front. At this point I would have thought two or three X one quarter mile walks daily would have been more than enough as it is only four weeks since your surgery.
Try heat or cold for the pain - -- - when you are in pain muscles tend to contract hence your cramps.Try drinking 250 Mills(one Glass) of Indian Tonic water at night(it contains Quinnine) which helps cramp situations
Things that might help you are a thigh pillow, which fits between your knees and stabilises your pelvis at night-time I think they are about $8. You can always just use an ordinary pillow for this if you wish, but three years after my surgery I still use a thigh pillow at night.
Also when resting on your back have a pillow behind your knees, that will help.
If you have a member of the family who can massage your gently then there is no problem with that.
I'm not sure what you're doing on these "stretching exercise" front, but the only ones at this point in time I would suggest you are the ones in the FAQs for your hamstrings and Achilles tendons.
We all want to get better quickly, but after the amount of surgery that you have had its going to take quite a bit of time say three months before you feel a big benefit, and certainly 12 months before you're totally pain-free I would think maybe.?
You know my old saying
"Slow and steady wins this race"
Best wishes,
Alastair