What Causes Twitching In A Kid After Taking Calpol?

hi, i took my 4yr old 2 the doctor and her temp was 38.9 nd they said she had thrush on her tongue/throat, i couldnt pic the medication up as the chemists were closed, ive given her calpol, then she was sick. shes asleep at the min but every 10/15 mins shes jumping/twitching as though shes gettin a fright. what is this? ive also gave her calpol about 30 mins ago and temp is 38.