Multiple Sclerosis (MS): Given the patient's age and symptoms of bilateral upper and lower extremity paresthesia, along with acute mid and low back pain, MS is a strong consideration. The disease often presents with neurological symptoms that can include paresthesia, fatigue, and unsteadiness.

Peripheral Neuropathy: Conditions such as diabetes, vitamin deficiencies (e.g., B12), or alcohol abuse can lead to peripheral neuropathy, which might explain the paresthesia in hands and feet.
Radiculopathy: Compression or irritation of the nerve roots can cause pain and paresthesia in the extremities, corresponding to the dermatome of the affected nerve root.
Spinal Stenosis: Narrowing of the spinal canal can compress the spinal cord or nerve roots, leading to pain, paresthesia, and fatigue, especially with activities that exacerbate the condition.

Spinal Cord Compression: Conditions like metastatic cancer, epidural abscess, or hematoma can compress the spinal cord, leading to rapid progression of neurological deficits. Early diagnosis is crucial to prevent permanent damage.
Guillain-Barré Syndrome: An autoimmune disorder that can cause rapid onset of muscle weakness and paresthesia, potentially leading to respiratory failure if not promptly treated.
Transverse Myelitis: Inflammation of the spinal cord, which can be caused by various conditions including infections, autoimmune diseases, or MS, leading to sudden onset of neurological symptoms.

Vitamin B12 Deficiency Myelopathy: A condition that can mimic MS or other neurological diseases, caused by a deficiency in vitamin B12, leading to subacute combined degeneration of the spinal cord.
Tabes Dorsalis: A late manifestation of syphilis affecting the spinal cord, leading to loss of coordination and balance, along with pain and paresthesia.
Sjögren's Syndrome with Neuropathy: An autoimmune disorder that primarily affects the exocrine glands but can also cause peripheral neuropathy and other neurological symptoms.

The workup should include:

Detailed neurological examination
MRI of the spine (cervical, thoracic, lumbar) to evaluate for spinal cord compression, MS, or other spinal abnormalities
Electromyography (EMG) and nerve conduction studies (NCS) to assess for peripheral neuropathy or radiculopathy
Blood tests for vitamin B12, folate, and other nutrients, as well as screening for autoimmune diseases and infections (e.g., syphilis, HIV)
Lumbar puncture for cerebrospinal fluid analysis if MS, Guillain-Barré Syndrome, or infectious causes are suspected.