waekness in arms and shoulders?

mw doesnt know what's causing it so wondered if you have any ideas?

in the beginning it was once a week or so for like 20 mins....now it's much more often... i feel a weakness in my arms and shoulders... like i had been using them all day everyday but i havent done anything..it's not weak like i would drop something but i do feel i need to lie down...or rest and then if goes away normally though not always..

i thought it was low iron but seems worse on days i take my tab(not sure of exact levels till appt later today) then i thought it was tight clothing but not any of that.. i can do whatever i am doing through it but its a weird annoying feeling .. :( any ideas?

thanks for that site.. it could well be!!