My lo is one week old and I have been breastfeeding and formula feeding. I pumped and gave her breastmilk burped her and laid her in her bouncer . She spit up a yellowish stuff . This is the first time she has ever spit up yellow. Is it normal ? Has anyone had any experience in this? I called the pediatrician but they suck I had to leave a message and the recording said it may take 24 hours to return my call. I don't want to take her to the doctor if it's normal.