Why am I suddenly getting my period twice a month?

Ever since I could remember I've had my period once a month. In April I had it from the 7th to the 13th. Then in May I had it from the 2nd to the 7th. That's fine. It was just one week. One the 29th of May I had my period once again all the way to June 4th. Today I wake up and I have my period again and since my periods are a week I expect it to last until July 2nd. I'm 19 BTW. I'm a virgin and I've never fingered myself or put anything down there like a vibrator or a tampon for me to bleed like that. I've never been to the gynecologist either. Am I under some stress? Yes. I live in an abusive home where my mother and brother continuously bully and mistreat me everyday. I'm saving up money for the fall so I can leave and live in a dorm. I try to exercise 5 times a week by jogging for 4 days for 45 minutes each and walking the fifth day. I try to eat healthy too. This morning and yesterday I had onions, tomatoes, canned green beans, and canned corn on top of lettuce with a side of water. Today I had french bread with butter and milk on the side. So why is it that I'm having two periods a month?