Answer: Shunt might have got blocked
Explanation:
As Derrick persist spina bifida , in which spinal cord of the child is not able to develop properly from the time of birth .So, he has got a shunt placed in the body for the movement and passage of fluid so that it does not result in hydrocephalus in which the fluid tend to settle in body and cause headache.
According to the situation, Derrick is getting irritated and not interested in playing outside as he is facing headaches displays that his shunt might have got block due to which fluid has deposited in the body causing the headache.