Ladies. Low fluid!

Ja

I'm 37 weeks and suddenly gaind 4lbs over night. Was at the doctors(high risk only so nothing but ultrasounds)today and they said my fluid is concerningly low. My BP and protein was good, but they aren't too happy with the looks of it. They said I need to get a cervix check and a amionic check again by Wednesday by regular ob or L&D. I'm drinking up as much water as I can but has any seen this this late in pregnancy? I dont believe my water has broke yet. I haven't even seen a mucus plug. Advice?:( I read that I could end up getting induced earlier than planned (this Sunday is planned) and it could even mean a csection.