A client status-post 48 hours external fixation placement of their (L) femur suddenly becomes anxious and restless. Assessment findings include increased RR to 28 breathes/minute and HR to 110 beats/minute; (L) foot and toes are pink and warm to touch; capillary refill is +2, with slight swelling present and a slight macular rash present on the client's upper arms, chest and neck. Based on their presenting clinical signs and symptoms which condition is the client most likely experiencing?

A. Acute osteomyelitis.
B. Post-traumatic stress.
C. Fat embolism syndrome.
D. Compartment syndrome.