This patient has acute worsening of right foot pain consistent with a stress fracture, which most commonly occurs in athletes (up to 15% incidence in runners) and non-athletes who suddenly increase their activity.
Bone responds to mechanical stress by remodeling, but an abrupt increase in intensity, duration, or frequency of physical activity (without adequate rest) causes repeated tension or compressive stress to the bone.
This can lead to micro fractures that eventually coalesce within the cortical bone.
Female runners with the “female athlete triad” (ie, oligo-/amenorrhea, decreased caloric intake, and osteoporosis) are more likely to develop stress fractures.
This patient’s menstrual irregularities and low body mass index make this more likely.

Option A: Morton neuroma is associated with pain between the third and fourth toes on the plantar surface and with a clicking sensation (Mulder sign) that occurs when simultaneously palpating this space and squeezing the metatarsal joints.
Option B: Plantar fasciitis causes burning pain in the plantar (not dorsal) area of the foot that worsens with the first steps in the morning.
Option D: Patients develop burning, numbness, and aching of the distal plantar (not dorsal) surface of the foot/toes that sometimes radiate up to the calf.

Reference : Essential orthopaedics by Maheshwari and Mhaskar, 6^th edition, Pg.no.159- 167.

Neck