Flu after a flu shot? Or allergies?

So I got the flu shot on tuesday and today is friday.  I doubt the flu shot has totally made me immune to flu that quickly so I got a feeling I can still catch a flu.  But I'm thinking...maybe it could just be the cat allergies I have from the day before.  I went to my girlfriend's house and she has a cat, I had bad sneezing, runny nose, wheezing, coughing...it all went away until night time when we left her house and was at my house for several hours, I still had a little wheezing and some stuffed nose.  My girlfriend is gone and she wore clothes that had no cat fur or anything on it and today I have a REALLY sneezing and runny nose.  And my mom has a sore throat out of no where and I hugged her yesterday and spent time with her for thanksgiving.  Mind you at 2 am when I was talking to her I was totally symptom free.  Then today I got symptoms.  Is it possible to get sick AGAIN?!  I took tons of time off work because I went through opiate withdrawal and I'm already 17 days clean but I know it messed up my immune system for a while.  Can cat allergies manifest themselves again the second day after being exposed and the symptoms went away?  Or am I probably catching a damn flu after getting the louzy flu shot?  I didn't get swine flu and my biggest fear is that my mom has the one flu I could catch or maybe I can get the flu the first few days after the flu shot since it takes a little while to be effective I think.  

And when do the flu shot symptoms appear?  Because I know flu shots have symptoms that are like a minor flu...