What Causes Repeated Leg Cramps At Night Followed By A Huge Bruise?

Question: My Mother has leg cramps during the night. Often after a bad night, she will have quite a huge bruise in exactly the area of the cramp. Research online shows me that many people are experiencing a bruise after a nightly leg cramp, and they range from healthy teenagers to the elderly on medication. The solutions re across the board, and doctors seem to have little information. She spoke to her doctor and according to my mother she said it was nothing to worry about. She spoke to a friend on the phone whose husband experiences this, and the friend swears by magnesium supplements as it worked for her husband. My mother is on the following medications:

-atenelol (high blood pressure .. norml now, but regulated by)
-lipitor (cholesterol ... normal now, but regulated by)
-calcium (weekly good dose)
-Vitamin D
-one low dose orange chewable aspirin per day
-puffer: subutimol (for emergencies of shortnes of breath due to COPD and bronchitis)
-puffer: advair (for COPD taken twice daily, morning and evening)
-puffer: spiriva (for COPD taken once daily)

The problem is that it is happening weekly and causing her to lose a lot of sleep. Do you recommend magnesium, or some other technique?