I need help with a very clingy 7month old

I had this same problem with my son. I think it has something to do with them not knowing that you are going to come back for them. At that age, they don't understand the idea of permanence. Meaning that they don't know that you exist unless you are there. It is a comfort thing to be close to you. What I did with my son, is I would strap a carrier to my chest and just walk around with him. Yes, it can be very tiring, and they can get in the way of your doing other things, but at least you won't be going crazy from the screaming! Have you also tried bouncy seats, or swings? Sometimes babies will find that motion to be very soothing.