I wouldn't remove the pup from its littermates but would give Mom time away from the pups. I have a litter of 6 week olds now and they are eating plus nursing. Their mom spends a lot of time with them but is getting to be less. She usually nurses them,diapers them and then lays up away from them on a small couch I have in their room. She also is just coming out more and leaving them for longer periods. Maybe your mom needs more time away from the pups. The playing is normal but shouldn't be excessive. It's just a judgment call as to what you think is too much. Sometimes they can get a little carried away with it.
On a side note, there was link posted recently in the breeders' forum about Esbilac. Here's the link....
LA Animal Watch: Petag's Esbilac puppy milk contains heavy metal copper
Goat's milk would be a good safe choice for soaking their food in until you go to dry kibble.