My little one will eat and burp afterwards, and a little while later she will spit up ALOT.

Could it be the formula ( similac advance ) ?

Also , some days she will poop fine daily and then stop up to 2 days and just push and nothing comes out, she also gets really red like she’s in pain while pushing. & then she’ll have a big blow out .. is that normal ?

She has an appt with her doctor tomorrow just wanting to get some help before hand so I know what to ask him .