A syringe if you are desperate would help, and you may want to do pedalyte if the point is hydration. As far as getting him to drink more on his own, does he like to eat/drink what you are eating/drinking? My son loves drinking out of my water bottles, yes, they are messy and we get water everywhere, but he seems to like it (even when coughing and sputtering). Also, take all of the sippy cups that you have offered him and try them yourself. Most require them to bite down and then suck to get anything out of them, and require so much suction, it is a wonder that kids can get anything out of there. Gerber's Nuk is more like a breast and the Born Free pour more easily. My son is almost completely weaned now, and the Nuk did it for him. He will also take sips out of the Born Free, but I have to help since the flow is so fast. Also, a normal cup may help too, you might just want to sit outside with that one. Good luck!