Quit job for offer. Now offer could be recinded. Other job hanging in the balance.

I left a huge tech company to pursue an offer for a smaller company for a lot of money. Well there was never any discussion about a master being required. It said on the job description masters or relevant experience. I did complete 5 full time years at university. I put this on my resume. Now I’m in a situation where the new company’s HR lady called me back to say (a week before I start) sorry but I notice you don’t have a masters and also, you didn’t finish your degree? (By 2 classes mind you). This is a huge issue I need to talk to 3 other people to make sure we plan to move forward. Basically threatening to rescind my offer. Well I don’t have much time with my current job to take back my resignation. In fact I think tomorrow would be that last day. The new job who threatened to rescind hasn’t called me to confirm, it’s been two days since they told me they migh rescind the offer. I’m in such a pickle. Do I go back to my old job and just say hey, they new job didn’t work out ? Do I contact the new company and say hey I need and answer? Do I wait ?