I am 69 years old. For years I regularly suffered leg cramps. About 2 weeks ago I had a B12 injection following finding of low B12 level. Since then no leg cramps. Coincidence? Maybe. But, if you are over 60, or vegan or on an antacid proton pump inhibitor like Nexium you may exhibit low B12 abosorption. A simple blood test can determine your level.