HELP! Severely constipated 😖

I am 4 days away from having my baby and I am severely constipated. I talked to my doctor and she said I could take colace but to be careful because it could cause my to go into labor early, which isn't a bad thing. But I really would like something more natural. Im drinking water like I'm never going to drink again, I eat plenty of fiber, I've resorted to drinking things that would normally make me go and have had no luck either. I just don't want to go into my c-section in 4 days already constipated and it be twice as bad after.