Please help

My 4 1/2 month old fell off the bed yesterday at 11am. She probably hit her head on the base of the bassinet. She had a red mark on the back side of her head. I had stepped out of the room to heat up her bottle. My husband was vacuuming so I didn't hear her fall. I heard her crying and went to check, saw that she had fallen. I took her to the Pedi, she said that she looked fine to just watch her for the next 24 hours. Yesterday she was great. She ate, slept and played just fine. But today is different.. she is not eating much at all. Normally she eats 4 to 5oz a feeding now she is only taking 2.5 to 3 oz a feeding and is more fussy. Must note that she hasn't pooped in going on 3 days. She is still playing, talking and smiling. I called the doctor she isn't concerned... she thinks her issues today are more from not pooping.

I'm so worried. Please anyone have this happen. Were your babies ok?