EDIT: I tried logging the exact same way, except from Electrical Engineering (the first community I joined), and this time it worked. I though where you tried to log in had no impact on your Stack exchange account, turns out it does. Thanks everyone who answered!
Some time ago I created this very account, using the same phone I am using now. My problem is, I have no idea how I created the account.
I apparently used neither my usual mail address nor my usual Google account. When I log out then back in with this phone, it works using a Google account but I suspect it is my friend's, who logged multiple times on other Google apps on my phone.
This account doesn't have much, and I could easily create another, but I don't like creating multiple accounts just because I lost one. Help?