If she's that strong I'm surprised she hasn't fought this cold off herself. Her white blood cells would literally battle the virus in a round of fist-cuffs.
Just mix the powder with a spoonful of honey, put aside some iced sweet tea on the side, and some jelly or a banana.. Works well enough for me as i absolutely hate those powder medicines up until i'm in a junior high..
Pinch the nose, wait 'til she breathes through her mouth, stuff the powder down her throat then quickly cover with your other hand. Classic family solution, don't mind the choking hazard.
That said, tough enough muscle and/or skin to block a syringe? Sasuga Big 7!
Ouch. Thank god that syringe didn't penetrate her skin though. If you inject a syringe when your muscles are pumping up, well.... Welcome to the world of pain.