is anyone else noticing already that their baby may be lactose intolerant?

Just looking for some stories for comparison.

Kinsley had a blistered butt the first few weeks of her life, something I never really thought much about (the “why?”) until yesterday. At five weeks after we found out she had reflux and colic I stopped eating and drinking dairy to see if it would help. So much was going on at the time (including the doctor putting her on Zantac), that I never really knew if it helped.

My milk dried up at 6m and so we switched to formula and we struggled to find something that worked for her until we switched to Holle.

Well at 10 months I tried to switch her to stage three before transitioning to milk at one year and it seemed like she was having tummy aches. So we switched her back to stage 2

At her one year check up the doctor said hold off on milk until 13 months.

(I should probably point out she eats yogurt and cheese regularly with no apparent problem, but now I think maybe I should pay attention to difference in her stools those days.)

Fast forward to yesterday and she was pointing to my coffee cup adamantly because “she wanted some”. I make her little expression cups of foam milk (with an ice cube to cool it down). So she can “drink coffee with mommy”.

I normally use unsweetened almond milk, but I was out. I decided to use regular milk bc she’s now 12.5m and I know we have to try it at some point. So I made foam and gave her like a tbsp of foam of which she only had a few sips.

Hours later she screamed bloody murder after pooping and when we took off her diaper her butt was bright red. We put pinxsalv on it, which normally works wonders and it was worse by bedtime despite only having we diapers. Thankfully this morning it’s cleared up, but I’m wondering if it was the milk?!?!

Has anyone else dealt with acidic poops or pees?

Could it have been the milk?

Any thoughts?