I've had this issue on occasion with my kids, and I have no idea why they are fine one day and not ok with it the next.
We tend to stick mostly with the liquid meds. One of my sons didn't want me to give it to him, so I allowed him to use the dispenser after I measured it, and he sucked it right down every time. When I tried to give it to him - he hated it and fought me. It seemed to be a control issue for him. We also tried different types of dispensers (the test tube looking type, the syringe looking type, and the eyedropper) and he had a favorite.
We also tried the melt-in-your mouth type of little tablets or paper-like strips of meds. This is a big hit with all my kids, they love it!
None of them like the tablets too much, even if they are flavored.
When all else fails, I do mix it into a sweet drink or applesauce. I don't let them see me doing it. If they are very sick and unlikely to drink a large drink, I only give them a half serving of drink, so it's more likely they'll get all the meds.
And as a last resort, I use the eyedropper and hold them down and squirt it way to the back of their throat. Hate doing this, but it also works.