Last night, I was woken up by severe pain in my calf, easily the worst pain I've ever felt. I couldn't even move my leg, and my calf was unusually hard and painful to the touch. After forcing myself to move my leg, it mostly subsided, and I went back to sleep. When I woke up for good this morning and walked around a bit, I found there to still be traces of pain, but its mostly gone. Is this something serious to be worried about?