That draining sensation is the recoil from carrying hard in a game. It's natural and it leaves you not wanting to play league for a bit so you can wind down.
Went 27/7/19 in the game prior to posting this. All of my allies fed. None of them went positive. And the enemy jungle was taking half my camps. But I dug deep and ganked and ganked and ganked and ganked and...
ganked
Wherever I saw an enemy caught out, I didn't care if they were fed or not, I just threw all I had at them and obliterated one target after another. I claimed every dragon I could, killing the enemy jg each and every time he tried contesting it.
I was truly terrified of dying in game because the enemies would almost certainly take another objective knowing I couldn't stop them.
And when we had one opening at the enemy base, and my allies wanted baron. I said "No" "base" and they listened and we won one final team fight with heavy casualties on both sides myself included, but our two survivors persisted and ended it.
And it was exhausting and draining.