My hand hurts for no reason?

So basicly back of my left hand hurts around the wrist for no reason and I am not sure, if I should go and have it examined. I first noticed it yesterday when I tried to support myself on it, but it felt like something was allready wrong. It is not like it hurts all the time, just when I bend it forward or push on it (makes getting up a bit complicated). It feels tender otherwise. I asked my mom about it and she observed it looks inflamed and feels hotter than the other hand. Any ideas what could be the cause?