sick toddler!?

my toddler began having a fever with no other symptoms, but he did threw up a teeny bit of milk once, for one day only. he doesnt have any diarrhea too. on the 3rd day of having fever, he started throwing up a lot. is it because he has the stomach flu and it didnt show up until the fevers about to be over? also, he is starting to cough a lot now, he sound like a sore throat is coming. could this fever be because hes starting to have a sore throat or even stomach flu?