I Have Pain In The Middle Of The Ball Of

I have pain in the middle of the ball of my foot just below the base of my middle toe when i walk on it. There was no incident that caused it. It just came on suddenly in the morning. When I sleep on my back with my feet straight up, the weight of the covers induces some mild discomfort on both feet that goes away when i turn them sideways. What do you think might be the problem?