Hi, Autumn--
I have that anxious voice sometimes, too, and for me what worked was therapy and meds. It took both to get the voices to adequately shut up, although therapy is most important, I think, if you can find someone good. I am glad you recognize that that anxiety you feel isn't you-- it is something happening to you, and it is absolutely worth addressing. I would go after it the same way you would any other physical ailment-- go to the doctor and get recommendations, do everything you can to fight it. Lifestyle stuff helps, too, as people here will attest-- all the stuff you know already (exercise every day, healthy food, getting outside every day, vitamins, being around positive people) that is hard to do when you are in a "mood" but which helps enormously if you can get yourself out and about to do it. When I have been at really low points I would actually "prescribe" myself little outings to make myself get out and exercise and be in the fresh air-- it helped a lot. Anxiety flourishes when it is left to act on a captive mind-- getting out and about and thinking about other stuff helps vanquish those obsessive thoughts.
Good luck and keep posting.