My 6 year old son received his flu vaccine 9/23. On 10/4 he was lethargic, complaining of a stomachache and had a fever of 102. That evening he vomited three times and I gave him medicine to help him sleep. He has eaten little and continued to run a fever every day. He became congested on Monday 10/6. On 10/6 my 2 year old daughter began a fever. She had difficulty sleeping due to congestion. She has a limited appetite, mostly fluids, and has slept most of the day. I haven t taken them to the doctor. I believe this is a reaction to the flu vaccine and a mild case of the flu.