Too Much for Grandpa

Right now I am working part time because I wanted to be home with my son. My hours are 9-6 on my two true full days and on those days I don’t see much of him, and I couldn’t imagine doing that all week. While my husband and I are both at work my dad has been watching him. At first it went really smooth, but then my husband had to go to first shift for training and my dad began really struggling. My son will scream and cry for an hour because he seems to just not like my dad much. It’ll start as soon as we close the door and leave. Daycare is not an option, and I really appreciate all of my dads help but it doesn’t seem to be going great anymore. My son is almost 5 months and my dad and mom have been watching him while I work since he was 6 weeks. For the last month and a half the screaming and crying has been going on. I don’t know what to do because I can’t find something I can do from home, but the fact that my son is so upset is really bothering me.