is negligible.

Since this is only in one leg?...I'd wonder about your back.
Electrolyte things mostly manifest globally..and do not favor only one place. It is possible your problem is still not serious and only hitting on your leg if it has some injury or weakness.

Benzos are used as muscle relaxers. When they wear off, or you become habituated on them physiologically, you may get muscle spasms etc. Another thing that causes twitching is
low blood sugar. Up to 70% of people with low blood sugar get twitches as symptoms.

I would buy a quality magnesium supplement and see what happens. Do only that one thing..to see what the effect of it is. If you mix supplements you cloud the issue.
Just do not get the oxide form. And do the magnesium consistently for a month, to see if it benefits your problem.

Imbalances of calcium to magnesium often confuse muscles.
You are not getting any mag from your supplement.
There are food sources for magnesium that you can also do.
This thread has explanations about "sources".
here is another online example:
http://www.hoptechno.com/bookfoodsourcemg.htm

If you are training for running marathons, I would seriously hope you are eating properly.
I'd also get a good foot doctor to look at your ankles and feet.
Many muscle and pain issues can come from there.
If your legs are of unequal length, or you have any pronation issues, you will make them worse and strain your whole leg and back with stressful activities.

So I think there are other factors for you, including your electrolytes.
Come back after you do the magnesium, and if it does not work, I'll address the birth
control issue. Hormones deplete nutrients. B-complex especially. You can do a Bcomplex 50mg
if you want to support that in the meantime. Many athletes take B-complex for the B6 in them
to enhance muscle functions. Pyridoxal made in the body from B6 is stored in muscle.

Take care.