Loveable, don't be taking any potassium if you've been told not to!

That being said, its usually the magnesium that does the trick for cramping / charlie horses. Magnesium should come with calcium - the two work together helping with muscle contraction and relaxation. Magnesium actually allows the calcium (and other minerals) to work.

RDA for cal is 1000mg, RDA for mag is 500mg. Look for something with a 2:1 ratio (cal:mag) and take the dose throughout the day (the body can only absorb so much at once). One pill before bed will greatly help with night cramping.

Make sure the calcium is chelated, though. You want malate / citrate but not carbonate from oyster shells (its harder to absorb).

Cheers,
Nat