I need help

So I have been a stay at home mom since my son was born 8 months ago.  But just recently whenever I put him on the floor an I walk away to go do something he has a mental breakdown. He will scream at the top of his lungs an he won't stop till I pick him up. Now if I sit him down in the room I'm going to be at sometimes he doesn't start crying or screaming. So basically he always wants to be held. How do I get him out of that habit or get him to realize that I'm not leaving him or when I go to take the dogs out.?