Any mamas deal with their LOs projectile vomiting after eating rice cereal? Is this normal? Or a sign of allergy?

We started solids when LO turned 6 months old and she was fussy eating it but ingested it well without any reaction. Fast forward a week later, she ate rice cereal along with peas, sweet potatoes, etc and 2 hours later, BAM. It was so heartbreaking to see her go through the vomit session but once she was done she was back to normal. At that point I just stopped all solids trying to figure it out.

We talked to our Peds and he said some kids do that and the variables are too great to figure out why but encouraged us to put her back on solids again.

We tried again, only giving her less than 1/2 tablespoon and 1 hr later, the vomit sessions began again.

I'm doing my best to figure this out but I am at a loss trying to know where to begin. I know we need to try different foods to see what she can tolerate but I hate knowing that it may possibly make her sick. Rice cereal is a no go anymore but I am wondering if I need to change my diet (I've been EBF but she has had no problem with my milk).