Need help from other separated parents!?

I know being a separated parent isn't easy, and I know there are differences in parenting styled from each parent, but there are theings I've tried talking to my two year old sons dad about and its alomst like he doesn't care. A few examples are when he comes back to my home, he throws major tamptrumns over food, when I tell him " no" to things he knows at my house he doesn't mess with like the TV and such, he throws a fit and attempts hitting me. I know it isn't all my sons fault, but I keep my ground with my son to reenforce his good behavior at my home. Whenever I try talking to his father, or ask him about such behavior I get the same response EVERY time "he doesn't act like that at my house". I'm not stupid, it takes me about a day to get my son back into a good routine, such as naps, eating, and his behavior, then he's fine all week till he goes back to his fathers. I know he doesn't behave perfectly at his dads house. But now I'm hearing the same responses with other things, and they regaurd my sons health. For instance, three weeks ago, I got my son home and immediately took him to the ER b/c he had a temp of 105.9 and when I ask his father how long he had a fever, it was "he didn't have one when I had him" I know that a fever doesn't come on in a twenty minute car ride unnoticed. It turned out my son had bacterial pneumonia, from his dads filthy animals. This past weekend he came home with pick eye, again completely fine at his dad. I guess what I'm trying to ask, is there anyway I should bring these issues up with my sons father? Or do you have any other advice for me? I'm hanging in there but becoming half tempted to keep my son from going to his fathers on the weekend.