I'm an 18 y/o girl if it matters at all.
For years, sometimes the muscles in my arms just feel like they're on fire. The best way I can describe it is like heartburn in my arms. They get super stiff and it hurts so bad. I would normally guess it would be from exercising them too much, but that can't be the case (I've been sick the last couple days and just laying around). But I remember I've gotten these pains before just randomly, but never thought to ask about it. Right now its in my forearms, but it also happens in my upper arms. It gets so bad that I can't sleep when it happens, or if I'm asleep when it happens it'll wake me up. It also seems weird that it only happens to my arms. I know its strange, but any idea what I could be doing to cause this?
Trauma and vigorous use of muscles can cause long term pain thus rest is needed.. electrolyte imbalance is very very common in teenage girls, drink a lot of mineral water, eat bananas and take calcium supplements.. if you feel that you have done all that with no success, you need to consult the doctors about it.. there is a number of conditions that may present with tendonitis and/or myalgia from simple viral infections to thyroid condition.. and even cancers like Osteosarcomas (they are ALL age appropriate).. I am not here to scare you or make you loose sleep over it.. you did mention that you were unwell for the past few days, most viral illnesses (from common flu to Ebola) present with myalgia (muscle pain) and arthralgia (joint pain); and most fevers leave us with electrolyte imbalance of some sort.. give it another week, then go to seek help if it still persist..