Why Did I gain 5 Pounds in 2 days?

Ok so about a week ago i weighed myself and i weighed 118 and i normally weigh 112 or 113 I'm a 14year old girl and I'm 5 foot 3. i havent done anything differently or ate more or anything and it hasent gone down it just varies from 116 to 119 and i really dont know why. well bout a weeek ago i was eating a ton of buttered popcorn but i stoped because i realized that might be the problem but that hasent done anything and I have alittle bit of stomach surface chub or fat or what ever. thhat i usually dont have. and also i dance for an hour about 3 or 4 times a week and im a vegatarian and i dont like sweets.