Fluttering Foot!

i am writing in regards to a relative who is searching for info. concerning “What Causes Fluttering Foot” this has been going on for 5 weeks!
The fluttering has been going on in increments of 5 minutes than stops starts up again.
last few nites my relative has noticed it stops as soon as she gets in bed.
sometimes it stops for a few days and then starts up.
couple times the fluttering has not only been her foot but also in her same left arm.
Any info you can give me will benefit my relative. Thank You, CP Barney,