Hi and welcome,
Your question has landed in the MS community but there are other more common medical conditions or explanations for situation specific bilateral lower limb symptoms that would be more likely than a neurological condition like MS.
Potential explanations vary greatly depending on your age, general fitness and activity levels, general health, vascular health, peri to menopause, pregnancy, weight, diet etc etc, even something as simple as poor circulation during the night or incorrect foot wear can cause these types of problems....
IF you haven't already done so, i would suggest you see your family dr for a check up and likely general blood tests.
Hope that helps......JJ