I just lost all my ETH what do I do?

I check my MetaMask account nearly everyday just out of habit. Today I opened the app and realized I lost all of it, my account was drained. In the past transactions it said I transferred it to someone’s account at 3am last night. Keep in mind I don’t use any third party app, I don’t trade I was basically just holding onto the money for safe keeping. I’m not even sure how someone could’ve found out my account information unless MetaMask has a serious security issue. Any help would be very appreciated!!

(PS I didn’t touch the funds, never traded with them, didn’t fall for a scam and I didn’t click on a suspicious link. )