Nick's most likely suffering from a fungal infection in his nail. It is possible that this condition is onychomycosis.
The normal force(the force pushing up from a flat surface) is equal to the force of gravity (the force pushing down on the object) at 5N so they cancel each other out. The other two forces are going in opposite directions, one positive and one negative. Subtracting 10N-5N would give you the amount of force that is not canceled (5N) in the direction of the biggest force (to the left)
I think it might be hormones not sure.
