**Core Concept**
The patient's symptoms suggest a disorder of the inner ear or the vestibular system, which is responsible for balance and equilibrium. The presence of positional nystagmus and the absence of tinnitus point towards a peripheral vestibular disorder.

**Why the Correct Answer is Right**
The patient's symptoms are consistent with Benign Paroxysmal Positional Vertigo (BPPV). BPPV is caused by the movement of calcium particles (otoconia) within the semicircular canals of the inner ear, which stimulates the hair cells and leads to abnormal vestibular signals. This results in the characteristic positional nystagmus and vertigo. The absence of tinnitus suggests that the disorder is localized to the peripheral vestibular system rather than the auditory system.

**Why Each Wrong Option is Incorrect**
**Option A:** Meniere's disease is a disorder of the inner ear that affects both the vestibular and auditory systems, typically presenting with tinnitus, hearing loss, and aural fullness. It does not typically cause positional nystagmus.

**Option B:** Labyrinthitis is an inner ear disorder that causes inflammation of the vestibular and auditory systems, often resulting in vertigo, hearing loss, and tinnitus. The absence of tinnitus in this patient makes labyrinthitis less likely.

**Option C:** Vestibular migraine is a condition that combines migraine symptoms with vestibular dysfunction, often causing vertigo, nystagmus, and sensitivity to light and sound. However, the absence of migraine symptoms such as headache or photophobia in this patient makes vestibular migraine less likely.

**Clinical Pearl / High-Yield Fact**
BPPV is often associated with head trauma, inner ear infections, or other disorders that affect the inner ear. Patients with BPPV may experience relief from symptoms after the Dix-Hallpike maneuver, a diagnostic test that involves moving the patient's head in a specific way to provoke nystagmus.

**Correct Answer:** C. Vestibular migraine is less likely given the absence of migraine symptoms.