Trouble with In-Laws

I love my husbands family, but lately they have been disrespectful about how we want to raise our daughter.
They watch her while I work part time and my husband full time.
I am lactose intolerant and we just discovered that our daughter is as well. Lately they haven't been taking us seriously and feed our daughter milk, cheese and other dairy items. They say they give it to her because she likes it. 
I tried many times to explain to them that when she gets home she screams in pain while I try to get her to bed, and she doesn't sleep well. Not to mention she develops diarrhea that lasts for a couple days.
We are also a very modest family. I don't feel comfortable letting our daughter run naked outside, in the pool or in the house.
But no matter how many times I try to explain, it isn't taken seriously. She says it's normal and it's fine then let's her do it.
She is just a toddler right now but I still don't feel right about it.
Does any one have any advice? Am I over reacting?