The most common symptoms are:
-Diarrhea
-Gas
-Punctures and swelling of stomach
-Tiredness (because the diarrhea leaves you knackered)
-Moments of depression (when you think that you will not never exceed a and above you've had a bad day and all your friends are eating that chocolate cake and strawberries that you can't eat)
-Lack of vitamins (which can have as consequence the fall of hair, skin problems and nails...), because your body does not absorbs
But every body is different, and you will certainly have more symptoms than these.