Issues with MS Office Logging me out of documents shared via Sharepoint

I do a lot of collaborative work in Microsoft office and until around April of this year, it has always worked perfectly. But for the past 6 months, I have been getting randomly logged out of Word, Excel and PowerPoint while actively working in a document. I am then unable to log back in and have to quite all MS applications, open up KeyChain in Spotlight and delete all items under login associated with Exchange, Office and ADAL... This only happens when working in a document via sharepoint, and seemingly every 20 min or so. This makes collaborative work in Sharepoint now unusable. I cannot keep closing everything down and clearing the cache of logins in KeyChain. What happened and how do I fix this permanently?