If these come and go they could be Uhthoff’s symptoms. I get them when it is hot, I get hot (e.g. exercise) or when I am stressed. Just listening to my former boss’s voice on a conference call brought them on the other day – sensation returned to my hand once he stopped talking! I carry iced water in an insulated bottle with me to help manage them.
I hope you find out what is triggering things for you.