You cannot get sick from the injection version of the vaccine, the killed virus. Some people who say it causes them to get sick are likely people who were already sick and just in the incubation period of whatever cold or other illness they were carrying around. Some people do get mild fevers, redness/soreness at the site, and even body aches in response to the vaccine. But that isn't the norm and most people have no reaction. I want to scream every time someone says they got the "stomach flu" after they got the vaccine! If only they knew that real influenza was a respiratory illness, not a gastrointestinal one!
OP, you say you got symptoms of an upset stomach and whatnot, right? Well, that won't be cause by your life flumist vaccine. We're starting to get into cold season and whatnot, so you probably picked up some other nasty elsewhere, and symptoms just happened to coincide with the flumist inoculation.