I have not been much on the forum anymore but i have a question

I have a toxic(medicine induced) polyneuropathy and this is my 7th or 8th year with this.

this year i experinced from time to time cramp in both of my feet that made my feet arc somethimes very violently.
It can happen in the morning or if i have my feet on the coffee table watching tv but there are also periods that it doesnt happen at all

What does it mean?