BTDT. When the medicine *has* to go down and reasoning doesn't work, there is a quick, simple way. Got this from one of Dr. Sears books. Parent 1 sits on top of child, pinning child's arms to body with thighs, knees on side of head. Parent 2, with dropper ready, holds child's nose shut. Mouth will open, squirt medicine in, child must swallow to breathe, release nose when all medicine is gone. They are spitting mad, but the whole thing is over in less than 30 seconds vs. hours of wheedling and cajoling. HTH.
This made it much worse. He knows from our body language and gets really upset.
