Why won't Pokemon Go let me use my old Google Play Account?

I was playing Pokemon Go just fine, but a day later it froze at the loading screen. At the time I didn’t know about the airplane mode trick that would have easily let me play so I uninstalled and reinstalled the game. I put in my same birth date and then tried to log in with my same Google Play Account, but that’s where the problem starts:

When I try to log in with my old Google Play Account (The one with all my data on it) the screen whitens a little and the loading Pokeball appears. I’ve waited for hours and I didn’t even get to the loading screen!

I tried to log in with another Google Play Account and it worked fine, it’s just my main account that won’t work, and I really don’t want to start over.

I’m using a Samsung Galaxy Core Prime