What?! Why did I loose 10 pounds over night?

Please read my other question "why did I gain 5 pounds in 2 days" before you read this one. well i woke up yesterday and weighed myself and i was 105 naturally im 112 or 113 but lately ive been 116 or 117 and now im 105. usually i get into the ones ( like 105, 107, 108) when im sick but im not showing any signs of sickness. im a 14 year old girl and im 5 foot 2 inches in rather skinny compared to my friends but im not anorexic i dont even look that way. anyway, im a vegatarian and if you think i was or am pregnant no lol im a virgin. so if you could try to find and explanation i would be so less worried and no my scale is not broken i weighed mself again today and its the same. when i was like 117 pounds ( bout 3 days ago) instead of 112 ( bout 2 weeks ago) i tried the water weight theory: that if you drink alot of water the chub on my stomatch (that came out of nowhere and was never there before) and the extra like 7 pounds would go away well it wasnt working untill yesterday and now im 10 pounds less and i'm kinda scared is there something wrong with me?