Something's wrong but what?

My daughter is almost 3 months old and has been such a pleasant baby. We waited out the acid reflux that's so common in most infants and since 4 weeks old she has been an angel. Until yesterday morning. She has this tiny cough but no fever or runny nose or excessive sneezing. She sleeps for only a 15 minutes at a time, it's like a nap to get strength to scream some more. Mom's you understand what I mean, your baby cries when she's hungry and has another cry when she wants attention, and another when she's wet. But this is screaming crying so hard she can barely breathe and she's inconsolable. She gets the drops for gas because like I said she even has a cry for when her belly hurts. she's not pulling at her ears and I'm going to call her doctor for an appointment so they can tell me babies cry. But i'd really like some ideas as to what this could be before i go.Something is wrong and I dont know what and it's killing me to see her like this. can anyone give me any suggestions about what this might be? or what i can do to soothe her?