I see potassium and calcium but not magnesium. Have you tried that?
Sorry I cannot offer chapter and verse -- controlled, double-blind studies for your specific problem and how it might be related to magnesium deficiency. But if you read up on magnesium's basic properties and Google "DVT + magnesium," you'll find plenty of food for thought.
Including this from NIMH about muscle cramps and magnesium deficiency:
http://www.nlm.nih.gov/medlineplus/ency/article/003193.htm
The risk-benefit analysis of magnesium supplementation should include the fact that, unless you are a dialysis patient or for other factors magnesium is contraindicated for you, it's not going to hurt you and it could help not only DVT and cramps but also other magnesium-deficient symptoms that haven't yet come to your notice.
Chances are, if you're experiencing magnesium deficiency through muscles cramps, it's causing problems elsewhere as well.