Multiple Sclerosis (MS): This is a condition that affects the central nervous system, leading to a wide range of neurological symptoms, including tremors, numbness, and weakness. The numbness on the outer thighs could be indicative of a specific type of MS lesion affecting the spinal cord or brain. The age and gender of the patient also align with the typical demographic for MS.

Parkinson's Disease: Although less common in younger individuals, Parkinson's disease can present with tremors, especially with movement. However, the numbness on the outer thighs is not a typical symptom, making it less likely but still a consideration.
Peripheral Neuropathy: This condition can cause numbness and sometimes tremors, depending on the nerves affected. The distribution of numbness on the outer thighs could suggest a specific type of peripheral neuropathy, such as meralgia paresthetica.
Vitamin B12 Deficiency: A deficiency in vitamin B12 can lead to neurological symptoms, including numbness and tremors. This is a treatable condition and should be considered, especially if the patient has a history of dietary restrictions or malabsorption.

Spinal Cord Compression: This is a serious condition that requires immediate attention. Symptoms can include numbness, weakness, and tremors, depending on the level and extent of compression. The numbness on the outer thighs could be a sign of a higher level of spinal cord involvement.
Stroke or Transient Ischemic Attack (TIA): Although less likely in a young individual without risk factors, stroke or TIA can present with sudden onset of neurological symptoms, including tremors and numbness. It's crucial to rule out these conditions due to their potential for severe and permanent damage.
Neurosyphilis: This condition can present with a wide range of neurological symptoms, including tremors and numbness. Given its potential severity and the importance of early treatment, it should not be missed, especially in sexually active individuals or those with high-risk behaviors.

Wilson's Disease: A genetic disorder that leads to copper accumulation in the body, causing neurological symptoms such as tremors, and potentially numbness. It's rare but should be considered in young patients with unexplained neurological symptoms.
Friedreich's Ataxia: An autosomal recessive genetic disorder that affects the nervous system and causes progressive damage to the spinal cord, peripheral nerves, and the cerebellum, leading to symptoms such as tremors and numbness. It typically presents in childhood but can have a later onset in some cases.
Neurodegenerative Disorders (e.g., Huntington's Disease, Spinocerebellar Ataxias): These are a group of disorders that affect the brain and lead to progressive neurological deterioration. While they are rare and often have a family history, they should be considered in the differential diagnosis of a patient with unexplained tremors and numbness.