Robb has been sick, but he is on the mend. Because of his injury, he is prone to systemic infections, and he doesn't always recognize the symptoms before they escalate.
This is a very typical, and very serious health risk for people with spinal cord injuries.
Linguine likes the fact that Robb is spending extra time in bed. But we don't. Robb can't afford to keep still. Keeping moving is incredibly important for his well-being.