Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with your doctor.
Without the ability to examine you and obtain a history, I can not tell you what the exact cause of your symptoms is. However I will try to provide you with some useful information.
Regarding your tingling/burning, one possibility is called a neuropathy. A neuropathy is a generic term for some sort of dysfunction of the peripheral nerves. There are 2 types of nerves in our body, large and small. The small nerve endings supply the skin and sweat glands. There are two types of sensory neuropathy: small fiber and large fiber (depending on the size of the nerves affected). With small fiber neuropathies, symptoms including burning or buzzing or other vague symptoms starting in the feet and hands then in some cases spreading to other parts of the body. The other type of sensory neuropathy is called a large fiber neuropathy. There are several categories of this type of neuropathy, and there are many many causes. Sensory neuropathies can involve just one nerve or several nerves in the body. The symptoms are sensory loss and if motor nerves are involved ,weakness. Some types of sensory neuropathies occur and progress very slowly, others sort of wax and wane (with flare-ups) and some are progressive. One of the most common causes of neuropathy is diabetes, and sometimes only glucose intolerances, or abnormal rises in blood sugar after a glucose load can be the only indication (this is called a oral glucose tolerance test. Other causes include but are not limited to hereditary/genetic causes, autoimmune problems, vitamin deficiencies or excesses, some toxins, such as lead, arsenic, and thalium, abnormalities of protein metabolism, and other causes. Neuropathy can be assessed for by a study called EMG/nerve conduction studies (NCS) (tests done to check for neuropathy). With small fiber neuropathy, there will not be an abnormality, and a definitive diagnosis can only be made with a skin biopsy so that the number of nerve endings can literally be counted. There are other tests of the function of small nerves that can be ordered, such as QSART testing which looks at how much sweat the skin makes, since sweating is in a sense of function of these small nerves.
Regarding your twitching, one possibility is benign fasciculation syndrome, which I will abbreviate as BFS. It is a condition in which there are involuntary twitches of various muscle groups, most commonly the legs but also the face, arms, eyes, and tongue. If the diagnosis is confirmed and other causes are excluded, it can be safely said that the likelihood of progression or occurrence of a serious neurologic condition is low. It must be emphasized that in the majority of cases they are BENIGN meaning that they are of no consequence and are not resulting from a serious cause. In such cases, the twitches may be related to anxiety/stress, caffeine, and often occur after recent strenuous activity or muscle over-use. It is important in such cases to reduce stress/anxiety levels and to reduce caffeine intake.
However in general (and please understand I am not trying to imply I feel this is the case in you), when fasciculations occur in the setting of specific associated neurologic symptoms a problem in the nerve cell body (called anterior horn cell, such as in ALS) or nerve itself (neuropathy, as discussed above) could be present.
Your symptoms could have neurologic explanations which I discussed above, but taken in combination with your joint aches, sad mood, and multiple symptoms, it is important to consider depression as a possibility. 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. 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.
I suggest follow up with your primary doctor and you may benefit from evaluation by a neurologist as your primary doctor feels fit. It is important that you discuss your concerns with him/her.
Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.