When DS went through this from around 10 months old, people said it was separation anxiety. Oh man it was hard... My mum walked in to our house once and DS was hanging off my legs while I made his toast.

I don't really have any advice. At the time, I wasn't allowed to leave the room or his side actually to do anything, but it was just a phase we had to ride out. I did what you are doing - if I had to make his lunch for example, I would put him in his high chair or somewhere safe and go make it. He'd be screaming his head off, but I just wasn't interested in carrying him around all day - he was a big baby and I physically couldn't do it.

It's a phase, it'll pass, it's really hard while it's happening, but it will get better. And when you have baby #2, baby #1 will keep him/her company so it won't be as bad