Low fluid

So I'm getting nervous.  I was hospitalized last week (32 weeks) for low fluid.  They pumped me full of fluid through and IV for 2 days and sent me home.  At today's appointment, fluid was still low.  I am now on modified bed rest.  I drink tons of water and I am doing everything they tell me to.  Has anyone been put on bed rest for this?  Had low fluid?  Been told to wait it out?  TIA