Calcium is a player in leg cramps. Too much or too little, will trigger them.

So what is new? What drugs are you taking that are new?

What supplements have you done/changed? Think back to before severe cramps and after.

Use of a calcium channel blocker will set off cramps for example.

Low iron?

Try putting 1/2 of a lidoderm patch behind your knee at bedtime. Just above the bend at the hamstring level. You have these? This sometimes helps too.

Did you change your thyroid hormone?

Are they equal on both legs? (this tends to suggest a systemic issue)
If not , this suggests a irritated nerve on one side.

I used to keep a heating pad plugged in on my side of the bed. When I was working midnights I'd get them every day... and the heating pad helped.
(those were the days BEFORE supplements, and magnesium tho).

The 3 basic things that come to mind are Potassium, Magnesium and Calcium.
They have to be balanced. If you are taking Vit D in high doses, you can reduce your calcium supplement intake.

I think Quinine is useless (and dangerous).