@Daisy ******
I'm in the same boat. This is what I have found out so far: Ban Laem border crossing is still open but tomorrow is the last day. You can fly DMK to Siem Reap but they won't allow you to return the same day - as it's too late to fly there today, doing it tomorrow and coming back the next day will push you past the 22nd March certificate/insurance deadline. I've been told you CAN fly to Yangon and back in the same day, but need a Myanmar evisa before going which can take 1-3 days to approve. All 3 are a risk...I'm probably going to try the land crossing tomorrow morning 5am from Ekkamai bus station. Good luck