Allergy help!

Marianne
Doc is pretty sure LO has a food allergy. She's had colicky behavior, trace blood in stool (which is mucousy green), and the stethoscope picked up on lots of tummy activity. I'm a newbie to the allergy scene. I don't know anyone with food allergies and there are none in my family. I am on Day 5 of dairy-free and BFing. Symptoms actually seem worse yesterday & today. 
For the more experienced moms....
-is it too soon for me to be nervous that it's not dairy? Or did it turn out to be dairy but the symptoms get worse before they got better?
-my next appointment isn't until Wednesday afternoon. Is it too early to consider cutting out something else like soy? Her cries are so hard to hear...and she has more rashes than 3-4 days ago.
-For those that switched to formula, how long did you "experiment" with diet changes before making the change? Was it worth it? Also, are you scared the mystery allergy will manifest in a big way when they start on solids?
-what's your experience with infants who turned out to have multiple allergies?
TIA!