Im 20 weeks and 4 days pregnant. I've been having severe cramping for the past hour and a half. It…

Im 20 weeks and 4 days pregnant. I've been having severe cramping for the past hour and a half. It alternates between mild and severe cramping. I usually cramp after sex(about 6 hours ago) but never this painfully or consistently. Could it be Braxton hicks ? Im going to the ER in the morning because my doctors office is over 20 minutes away.