My account got banned after being hacked, what do I do?

Hey all, I just wanted to get a bit of peace of mind over this, and get people's opinions on what might happen in light of this situation. So I just tried to log into my account today to find it had been banned for usage of third party software, a claim that I can't even really begin to believe, since the only third party software I've ever used is Blitz, which I know is "use at your own risk" but will not generally get you banned on it's own. So I went in to check on my account's recently played games, only to find that someone had played two matches on my account almost three days after I had last played. (I just bought Forza Horizons 4, so I'd been playing that for about the last week.) So naturally, I checked to see if my email had been pwned, because I hadn't gotten any recent notifications on my email about anything regarding my accounts being logged in.

Apparently I had, which is no good, since it was on a game I had used the same password for as League, not a good idea, but things happen, I suppose. I changed my password on League, as well as my email even though that was a different password. My only question now is, what do I do? Does League know that my account would've been compromised? Can they even tell? I can verify I own the account, but I don't know any way to prove that I didn't play those games. I think the account was being used for boosting, since both matches were Kayle matches, and one of them was quite miserable, but even then, the players on both teams were all different for both games. I reached out to Riot just a little bit ago, but I am concerned about losing my account. None of this was in my control, and even now I feel sick to my stomach just thinking that I might lose all the progress that I put into my account. I never made alts, never cheated, and was generally not toxic either. If anyone has any words of advice, I'll make sure to keep posted what happens to my account in here. Thank you to anyone who cares enough to read my massive wall of text.

EDIT 1: An account named madoka84 played the two matches with my account before it got banned. I'm assuming that person was using the account to script or something. I don't even know.

EDIT 2: Riot support was kind enough to look into the issue, and lifted the ban on my account in light of the situation. Thank you to them for the help!