contractions!

I went into labor and delivery because my blood pressure got high and I was having a bad headache with nausea. while I was hooked up to the monitor they noticed I was having contractions every 10 mins but they think I am dehydrated so they sent me home with ice cold water. It's been about 4 hours since I left and contractions are still coming every ten minutes ! Is it possible this could be a slow start to labor ?