For 2-3 weeks i've had neck, shoulders, and back pains. loss of appetite. fatigue. hand numbness and tingling. depression. what causes these symptom?

Could be many things: While a simple viral infection can cause your symptoms, these could also point to something more serious. A good examination and blood work are in order.

Rule out med illness: You should first get a physicalexam to rule out any medical illness that might be contributing to how you're feeling. There are various illnesses such as vitamin deficiencies thyroid disease and sleep apnea that can cause what you're feeling. Lyme's disease is another possibility. Depression makes you feel very tired and fatigued both physically and mentally. You can develop aches and pains in virtually any part of your body. With depression you feel helpless hopeless worthless and guilty. Energy and motivation are low. There is a distinct lack of ability to enjoy things and a tendency to withdraw socially. You can either have an increased or decreased appetite and insomnia or increased sleepiness. You can also have both. If you are feeling this way please see your doctor, then a therapist, and if necessary a psychiatrist for medication management. Do not forget to watch your diet, exercise, and seek out other ways of treating your depression from an alternative medicine or complementary medicine point of view. Yoga, meditation, acupuncture, and finding your spiritual center can all be important ways to overcome depression.