What Would Cause Pain In Your Arms?
could be a lot of things.
Detailed Answer:
ok, so the bp is at a level that if it were always there it should be treated. There is the question of how someone gets dehydrated.
Cannot say in your particular case without seeing you, BUT statistically, by far the most common cause of dehydration is being on a diuretic. This also lowers certain salts out of the body, most notably potassium. The loss of potassium typically causes a CRAMP like pain in central muscles (arms, thighs) and in calves and forearms. It is rapidly treatable with orange juice.
Pain in distribution of place and time would imply causes. All over or multiple spots imply an overall condition and not a local muscle problem. Likewise, Pain that goes in waves is not so likely to be a local muscle problem.
Poking things and seeing what pain it causes is a usual way to tell what is going on. If the muscle is sore, then it isn't a joint (and it isn't heart). But the muscle could be sore either from a muscle problem (pulled muscle) or an over all problem (electrolytes).
Hope this is a helpful framework.