I had the same problem I had the injection then came down with the flu but I had the injection 2 years ago and since then I have not had the flu since even if im around ill people nothing, so give it a few days and you will start feeling a lot better .
Yes it is very common. You have to understand the shot is a dead of weakened form of the virus. Its just like getting sick but just so your cells and antibodies will memories the vaccine so when the real flu gets into you your antibodies have memorized it already with the dead or weakened form so you wont get that flu. So you are supposed to get a little bit sick from the shot.
This is from The Center for Disease Control Website for all of you posting the wrong info: Can the flu shot give me the flu?
No, a flu shot cannot give you the flu. Flu vaccines that are administered with a needle are currently made in two ways: the vaccine is made either with a) flu vaccine viruses that have been ‘inactivated’ and are therefore not infectious, or b) with no flu vaccine viruses at all (which is the case for recombinant influenza vaccine). In randomized, blinded studies, where some people got flu shots and others got saltwater shots, the only differences in symptoms was increased soreness in the arm and redness at the injection site among people who got the flu shot. There were no differences in terms of body aches, fever, cough, runny nose or sore throat.
More information about these studies is available at: •Carolyn Bridges et al. (2000). Effectiveness and cost-benefit of influenza vaccination of healthy working adults: A randomized controlled trial . •Kristin Nichol et al. (1995). The effectiveness of vaccination against influenza in healthy working adults. New England Journal of Medicine. 333(14): 889-893.