That set-up you have with copper piping and teflon taping is a 'Harry Homeowner" rigging. You can get all those parts at a plumbing supply store easily. As mentioned by dave_monica, you really need to support that flush line better. The weight of it bouncing up\down prolly loosened it up. Take everything apart and start at the tank fixture. The tank is ABS plastic so whatever you use has to adhere to that. Once that is sealed up real well, re-plumb and support all that crap. Good luck.
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