Dairy allergy? First time on formula today

My son has been getting pumped breastmilk since birth. He’s now 6 months and we started the transition to formula today.

We used Similac Pro-Advanced which contains dairy and soy. I gave him one bottle of 1oz formula and 5oz breastmilk. Little guy now has redness all over, bumps on face.

Has anyone else experienced this? I was so anxious about starting formula and then told myself it’s no big deal...now this. He’s acting totally normal and it’s not getting worse. Going to stick with BM for now and call ped in the morning.