Separation is a hard time for a young one. And for young ones, since they can't communicate well, his way of perhaps saying he misses his dad is to scream and cry.
Is he happy when he sees his dad?
My OH and I were separated for about 5 months, starting when my daughter was 17 months old. She couldn't wait to see daddy, was excited to go with him, etc. but when he had her for the days that were his, she screamed and cried. It's their way of showing they don't like the situation. Although she was happy to be with her dad, I think she missed mommy too.
It's tough I know! Don't really have any advice other than to be patient and hope that it sorts itself out.
