Baby won’t drink breast milk.

My baby is 8 days old. Due to latching issues I pump and supplement with formula. The last two days she’s refused to drink the normal 50/50 breast milk formula mix. If she does drink it she’s throws it right back up. She will however drink the formula on it’s on and has no issues. Now I’m wondering if it was something I ate? Would that affect the taste cus she gets one drop and wants nothing to do with it. It can’t be a milk thing cus she’s doing fine on the formula. Thanks in advance!