Baby sick since cows milk

Please help!!! I transitioned my healthy 1 year old to and organic pasteurized cow’s milk. I give him 6 oz when he wakes up and 7oz before bed. I believe the daycare gives him 2 6 oz bottles but I’m not clear. Since transitioning him, he got hand foot mouth disease and literally 2 days after he was better he got hit with an on and off fever it’s now day 3 and he is teething bad! The doc said it’s a viral infection no ear infection breathing good etc. he threw up last night but started running around the house playing right after. I might have fed him too much dinner (steak, blueberries, oatmeal and vegetables and milk only 1 he later) the daycare owner who I am very close with told me she thinks him being sick is because I’m giving him organic milk and to be ok with regular. I said of course I’m open and we’d try it for 1 week then transition to a milk alternative until we find out why he is getting sick back to back. He was never like this. But at the same time I wonder if it could be other things like too much dairy? On top of the milk I give him yogurt and cheese. Or it’s just that time of the year where kids get sick back to back to back? Mine was super healthy and now it feels like he’s sick all the time. A part of me wants to say just give him my organic milk but LESS and we will reassess but I’m nervous to stand up for myself because what if she’s right and I’m wrong? I don’t think it’s the milk making him sick I think it’s probably the amount but I’m nervous to tell her what to do because she has -7 years experience very successful with the kids I only have 1 year expedience with 1 kid