If your mood swings are affecting your life or your relationships, you could go to your regular family doctor and talk about that. Sometimes it's a really simple fix like getting enough rest or taking vitamin D or what have you, but he would also be able to make a referral to a therapist or psychiatrist if medications were required. To me some of the symptoms your describing about loss of interest, agitation, anger and negative feelings towards yourself are really classic signs of depression, sometimes you dont have to be diagnosed as anything in particular to get help. I mean in the very least i really think an anti-depressant could help you. Depression by the way is really common, something 90 percent of people have or will have it sometime in their life, so dont feel like your different then anyone else. I hope you get some relief, and keep posting let us know how your doing, and if you plan to make some changes and see a doctor.