Water, Water Everywhere!

hey guys,if anyone out there knows anything about plumbing I could sure use some advice. here's the short version. last night my washing maching lost all it's water in the middle of a load through the front bottom of the machine. all pipes and flooring is dry behind the washer. at the same time I find water under my sink. all pipes are dry. the wall is dry and when I ran the disposal it was also dry with no signs of a leak under the sink. All drains are draining.today I come home and my bathroom is flooded. there is an obvious leak coming from the bottom of the toilet tank but there is no crack or hole so I don't understand where the water is coming from since all screws and surrouding areas are bone dry. the wall is dry by the main pipe and all the water is coming from this steady drop of water from bottom of the tank, none from the base of the toilet or the wall. I stopped the water on the toilet and that stopped the leak even though the tank is still full of water. the kitchen is adjacent to the laundry room and the bathroom is behind the laundry room but does not share any wall with joining pipes. The toilet does however share a wall with my fridge which dispenses water and ice, no leaks so far from that wall. i called a plumber and they said it didn't sound urgent and maybe they could get out here Friday if I was lucky. Shoudl I panic? I mean more so than I already am that at any moment my house will be like the Titanic!