Without the ability to take a history and examine you, I can not common on the cause of your symptoms. However, I will try to describe some conditions which cause burning and tingling.
The cause of burning, numbness, and tingling symptoms depends largely on their distribution: what parts of the body they occur in.
(1) symptoms worst in the hands and feet: this can be caused by a process called a neuropathy. There are 2 types of nerves that provide sensation to the feet, large nerves and small nerves. A problem with either of these could lead to burning and tingling. There are many many causes to this group of disorders called "neuropathies". They include but are not limited to most commonly diabetes, vitamin deficiencies, autoimmune disorders such as lupus or a disease called Sjogren's, certain types of neoplasm, and certain toxins (such as lead). As I mentioned, there are several other genetic, metabolic, and hereditary disorders that cause neuropathy, and what tests need to be ordered depend on the history and physical examination of the patient. With small fiber neuropathy, the EMG/NCS test which measures how nerves conduct electricity and how muscles respond to them may be normal. In large fiber neuropathy, it will be abnormal. Small fiber neuropathy can be diagnosed with a skin biopsy and with a test called a QSART.
(2) Symptoms present on one side of the body versus the other, or in just one limb. Causes could include a stroke or the condition multiple sclerosis. These would best be excluded by an MRI.
(3) If symptoms migrate (move from one place to the other) and are intermittent, causes might include seizures, migraine disorder or metabolic problems such as low calcium.
(4) Often these symptoms may reflect emotional/psychiatric problems related to stress (what is called somatization disorder). The latter is a TRUE medical condition whereby instead of a patient experiencing depression or anxiety, they experience physical symptoms, and once the stress is addressed, the symptoms resolve.
(5) Fibromyalagia is another medical condition that leads to whole body pains, and is best treated with medications such as lyrica and neurontin, exercise, and physical therapy.
These are just some causes of burning/tingling. Continued follow-up with your doctors is recommended. Evaluation by a neurologist, if you have not already done so, is recommended.
Thank you for using the forum I hope you find this information useful, good luck.
Idiopathic neuropathy (numbness & you don't know why).
First you need to get all your symptoms documented by a service-connected physician/medical organization (MASH or clinic). It probably will have something to do with problems as you get older, which is why you need to connect future problems with your current service (service-connected). You'll need to see if your problems are vascular (blood vessels/circulation) or neurogenic (nerve-caused pinched nerve, etc), or a combination of both to know what to do next. Check with the VA, too. They might be able to help. Thank you for your service & good luck.