The stress of motherhood may be getting to Beyoncé. A source says the singer has hired an army of nannies to help care for twins Sir and Rumi, at a cost of $100,000 a pop! “The twins don’t sleep at the same time, so she decided she needs three per child, working in eight-hour shifts,” says the source. And that’s not including two caregivers for Blue Ivy, 5. Why not just ask Jay-Z to pitch in? He’s a source of more tension: Another source says Bey is giving her hubby the cold shoulder as he focuses more on promoting his new album — even heading out on a tour in September — than being with the babies. Uh-oh!