It sounds like a database issue. I have no idea how could that happen (especially when you haven't done anything), anyways your database is probably outdated. You may try to reinstall the plugins, they should repair themselfs, but you will also lose the data (medal assigments, thanks)
Can you tell us which extensions have you installed? There are at least 2 diffrent extensions for medals and for thanks. And copy here, what exacly debugger said. Maybe it can be fixed without reinstalling anything.