My daughter is almost 2 now, and she has had the same problem that your discribed since she was 3 months old. Everytime she gets sick I just wish that she won't need the antibiotics. Because she not only throws up the meds on spot, she throws up the entire stomach contents 2 hours after she has the meds (she has both acid reflux and emptying delay problems). So many times I just want to cry seeing her trying to eat because she is soooo hungry from throwing up only to throw up again in a hour.
Okay, so I know telling you our story may not help, but first I just want to let you know that you are not alone. Also, my daughter's problem is not related to the "flavoring" of the meds, so changing flavors does not help. It's the antibiotics itself that causes the throw ups.
So this is what I suggest since I live through it for almost 2 years - determine if she really needs the antibiotics. For example, colds -no. But my daughter had pneumonia twice and she really needed it. So know that her little body will reject it, and be prepared. If she throws up the meds right after she takes it, I would give it again till it takes. If she throws up after 2 hours, I would not give it to her again hoping some meds have been absorbed within the 2 hours. Get plenty of towels and change clothes during the week of meds. Try to take really good care of her so hopefully she will get better sooner than later (you know, fluids, good nutrition, rest) and won't need a second round of meds. I have an older child, so I know that almost all problems are just a stage and things will get easier in awhile. Best of luck to you.