Help!

My baby girl's behavior has suddenly changed. She is a month old and she now cries constantly. I feed her, burp her, change her and she is calm for 20mins and naps, but the wakes up and cries non stop. If I walk around with her she is ok for a few minutes, but nothing calms her. She is exclusively breast feed and I've racked my brain to see if I ate something different, but this has been going on for a week. Today has been rough, she has not stopped all day and will only sleep in short spurts.

She had her month checkup and the Dr said she was good, but this does not seem normal.

Any advice or guidence is greatly appreciated !