My Mail App on my iMac keeps asking me to reenter my password for my secondary account but it won't allow me to and has an error message of "authentication failed" before I even get a chance

I have an iMac and I've had this problem for a about a year. However it just compounded itself to make my mail unusable. So if I have to update my password for work (my secondary account) when I come back to my home computer it asks for an updated password. Yes, this is normal. However the pop up screen for my jobs email and password entry will pop up and before I can do anything else an error message pops up that says "Authentication Failed" and then it says underneath "Failed to Authenticate with Google, please try again later." So I just haven't been using my work email on my computer except through gmail.com. However the last time I sent an email from there I accidentally selected my outgoing email to be my work email and it had a meltdown. Now I can't do anything in my email because it is stuck on that "Authentication Failed" pop up. I have shut down mail, I have rebooted the computer and every time it reopens it pops up with the email and the "Authentication Failed" pop up.

Any help is appreciated!