If it's a persistent problem, a visit to the doctor is probsbly advisable.

Thermotabs (often called "salt tablets") contain potassium as well as sodium and other electrolytes. Sold at Walmart and Walgreens, but not in all areas of the country:

http://www.numarkbrands.com/products/thermotabs/

REI sells these "Medi-Lyte" supplements in little packets in their first aid section (note there's no sodium):

https://www.mfasco.com/first-aid-supplies/electrolyte-replacement/medi-lyte-tablets-250-x-2.html

I keep a few of each in my first aid kit.
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Always remember that you are absolutely unique, just like everybody else. -Margaret Mead