The Board has denied the veteran's claims of entitlement to service connection for a right ankle disorder, a right elbow disorder, and high cholesterol. The evidence does not establish current disabilities or a link between these conditions and military service.

The Board has determined that the AOJ did not obtain all necessary opinions regarding whether the Veteran's symptoms are related to an undiagnosed illness or medically unexplained chronic multisymptom illness (MUCMI). The claims for service connection for fatigue, fibromyalgia, left elbow disorder, right elbow disorder, and sleep disorder are remanded for further development.

The Board has decided to remand the Veteran's claims for service connection for lower back, right hip, and right ankle disorders as secondary to his left knee disorder. The AOJ must obtain VA examinations and provide answers to questions regarding the etiology of these conditions.

The Board denied service connection for treatment purposes only under Chapter 17 for various conditions, including cervical spine condition, right upper extremity nerve condition, left upper extremity nerve condition, headache condition, right wrist condition, left wrist condition, right elbow condition, left elbow condition, right shoulder condition, obstructive sleep apnea (OSA), bilateral pes planus, right ankle disorder, left ankle disorder, and left knee disorder.

The Veteran's tinnitus and hearing loss claims are denied as there is no current diagnosis of these conditions.,The Veteran's high cholesterol, dementia, stroke, prostate cancer, cataracts, diabetes, hypertension, CHF, and myocardial infarction claims are denied due to lack of service connection evidence or insufficient evidence to establish a nexus between the disabilities and active duty service.,The Veteran was exposed to toxins during his military service but there is no evidence linking these exposures to any of the claimed conditions.