The regular Robitussin DM has an expectorant which if you give that with a ton of water or juice will help thin out what is in there, and make it so they don't throw up from coughing so hard. Our DD was doing that too. It won't stop the coughing but makes it more productive (although it doesn't taste very good - we bribed with suckers). Also, good old Vicks Vapor Rub will help ease the coughing fits and helps break things up. That is how I've gotten my kids to sleep through this, by rubbing this on their chests and backs. Hope your little one feels better soon.