I have only had one period my whole life, and that was when I was 17 years old. I am now almost 28 and it has been over 10 years since my last period and out of nowhere I started my period. What I need to know is if this is something I should be worried about, should I see a doctor?

If you have checkups and are basically healthy, and have no complaints, I think you will find that testing might be very expensive and involve an endocrinologist, with possibly nothing being found. You could visit a GYN for a regular female physical with mammogram, pap smear, and ask for a CBC blood panel, especially hematocrit, which might be a clue to anything like anemia, but usually you feel tired and other signs of anemia. Intense athletics can stop the cycle. Can you think of anything that was slightly different about you for 10 years? Were you on any medication, or did you take any supplements, or go on any diets?
I had a roommate who had her own suite of 2 rooms and bath, and her periods stopped in her 30s (plus she was celibate at the time), and she was told to use our bathroom, and that started her periods again. It's well known the women synchronize cycles when living in groups, and possibly you just haven't been around enough other women.

Well when I had my one period when I was 17 I had lost 76 lbs, and then gained it all back, and recently I have lost 84 lbs and now I have started my period once again. Do you think my weight could have something to do with it?