Evidence for the existence of fine-scale (<10 km) heterogeneity within the Earth’s inner core (IC) has been reported over the last 20 years. However, the detailed structures and origins of the fine-scale heterogeneity are poorly constrained. Continued seismic mapping of the IC fine-scale heterogeneity is important because it provides a complementary picture of IC fabrics, which records the history and evolution of Earth’s core. Here, we observe and model seismic energy scattered from the IC and create a 3D model of inner core fine-scale heterogeneity. Our model shows that inner core scattering is ubiquitous and provides fresh insight into the growth history of the inner core. We explore IC differential rotation by studying the changes in forward scattering within the IC of P waves of earthquake doublets. We find that the inner core experienced a burst of differential rotation during 2001–2003. This fleeting bit of differential rotation helped excite an inner core rotational oscillation, consequently exciting the six-year oscillation in the length of day.