Dairy Allergy?

Hey everyone just looking for some advice here cause I’m feeling a little lost. !!!Heads up it’s a long one and there’s also the mention of blood!!! My little guy will be 12 weeks old on Monday. We started out with breastfeeding but unfortunately around the time we hit 1.5 months, my supply had drastically dropped and so we switched to formula (still was able to give him about a bottle a day of breastmilk tho). We started out on Similac 360 Sensitive. He was doing really good with it, absolutely no problems. But then we got on WIC, so we had to switch to Enfamil Gentlease & at that point I had stopped with the breastmilk all together. About 2 days after we switched, he had his 2 month checkup & got his first round of vaccines (Jan 23). 3 days later, I noticed he had blood in his stool. Me and my husband decided we’d keep an eye on it and if it continued we’d schedule an appointment. We ended up taking him in to his ped the nect afternoon (Jan 27). She checked for any anal fissures and didn’t see any, said it could potentially be a side effect from the rotavirus, could be from switching formulas, so to keep an eye on it and if it didn’t get better within 3 days to call the clinic. Well 3 days went by and there was actually more blood in his stool than there was since we first had noticed. So we called, they told us to go to the ER, ended up taking him to Masonic children’s ER. When we ran them through everything I mentioned above, and showed them the pics of his diaper, they did an ultrasound to check for intussusception (rare side effect from the rotavirus vaccine that can cause his intestines to move like a telescope essentially), an xray to check for necrotizing enterocolitis (inflammation of the intestine that can cause the tissue to die), and bloodwork to check his hemoglobin. Well all of the tests/scans came back clear. So they decided it was a cow’s milk allergy. So we switched to Similac Soy and didn’t have any problems up until today when his diaper was half poo and half blood. Took him to the ER. Made sure to tell him that since we made the switch last week there hasn’t been any blood whatsoever up until today. Basically they said that they think he might still have milk protein in his system but that doesn’t make sense to me because like I said, this is the first bloody diaper we’ve had in a week now but it’s also more blood then there’s ever been. I’m also confused because we honestly didn’t have any problems either dairy at all (considering I consumed a lot of dairy while breastfeeding) until around the time that he made the switch to Enfamil but also got his vaccines. I just feel so lost and I’m not sure I 100% agree with the doctor’s diagnosis. So if anyone has any advice on what to do next/other things to potentially look into, or similar experiences they’d like to share, this stressed out mama would greatly appreciate it🫶🏻 Pic of my little guy for anyone who suffered through the book I just presented lol