Cubital Tunnel Syndrome: This condition is characterized by compression of the ulnar nerve at the elbow, leading to symptoms such as numbness, tingling, and weakness in the hand and arm. Given the specific mention of "cubital tunnel," this diagnosis is highly plausible due to its direct relation to the symptoms and location described.

Cervical Radiculopathy: This condition involves compression or irritation of the nerve roots in the cervical spine, which can cause similar symptoms to cubital tunnel syndrome, including pain, numbness, and weakness in the arm and hand. The mention of a potential "cervical issue" makes this a likely consideration.
Thoracic Outlet Syndrome: This condition involves compression of the nerves and/or blood vessels that pass into the thoracic outlet (the space between your collarbone and first rib), which can cause pain, numbness, and tingling in the arm and hand. While less directly related to the cubital tunnel, it's a possible cause of similar symptoms.

Acute Spinal Cord Injury or Compression: Although less likely, conditions such as a herniated disk, spinal stenosis, or spinal cord injury could present with arm and hand symptoms and are critical to identify due to their potential for severe and permanent damage if not promptly treated.
Tumor (Neurogenic or Bone): Tumors affecting the spine, nerves, or surrounding tissues could cause symptoms mimicking cubital tunnel syndrome or cervical issues. Early detection is crucial for effective treatment and prognosis.

Peripheral Neuropathy: A broader category of nerve damage that could affect the nerves in the arm, leading to similar symptoms. This could be due to various causes, including diabetes, vitamin deficiencies, or autoimmune diseases.
Brachial Plexitis (Neuralgic Amyotrophy): An inflammatory condition affecting the brachial plexus, leading to severe pain and weakness in the arm. It's a rare condition but should be considered in the differential diagnosis due to its potential to cause significant morbidity.