hi, thanks for writing. i have understood your concerns. you have symptoms that classical for depression. persistent and pervasive sad mood with loss of interest in previously enjoyable activities indicate that this is a depression. you shud seek help from psychiatrist before it gets worse. body pain, lethargy, weakness and decrease concentration can be because of depression. in my opinion you shud visit a psychiatrist and tell your problems. depression is very common nowadays. it is called as common cold of psychiatry. you shud not feel shame in admitting it. even abraham lincoln had suffered from it. there are different classes of antidepressant drugs, which will help in resolving depression, they act at neurochemical level in brain. the effetcs of these drugs can be seen within 10 to 5 days of starting the drugs. I will suggest that you can attend psychotherapy sessions and support groups. cognitive behavior therapy is suitable to you,. i hope this advice will be helpful to you,, best of luck..