Suggest Treatment For Swollen Throat After Tonsillectomy

I had my tonsils out today and was given a medicine that is suppose to help with pain and swelling for 4 hours. It is only lasting about 2 hours and then my throat swells up and hurt really bad. I am chokin on water just to try to get some in my system so i do not become dehydrated since i am on a 24 hour liquid diet. what shoudl i do?