Did you follow the steps at https://support.google.com/accounts/troubleshooter/2402620 ?
Edit: the closest solution is to try account recovery, which is what I was doing. :(
I don't want to "spam" the recovery form, since I suspect that will only make it worse.
Edit2: trying Gmail app and Google Authenticator now, to see if that makes a difference. Will update with progress.
Edit3: no dice. Gmail app just loops me to a message saying "Google couldn't verify that this account belongs to you." Clicking on Verify account just loops me back to the login. It doesn't even ask for my old password like before.
I feel sick to my stomach...