Wow, I can't believe they sent you home too. Sounds like if it was two nights ago you obviously were not in active labour. How are your contractions now? Are you heading back?
My contractions have been ten mins apart since I was at the hospital have not changed
Hmm most hospitals won't let you leave if you're dilated at 4cm. I would go back and just have them check your cervix one more time.
I would definitely go back or at least call your doctor