What Causes Spotting With Pain In Lower Abdomen In Mid Of The Cycle?

Hello it seems that every time I get upset I start what seems like a menstrual cycle. I have slight lower abdominal pain. about a week ago I finished bleeding after 3 weeks of what alternated as a light to medium flow. I would think it was going away and then it woIuld woosh back. I am under a high level of stress and im kind of concerned that I might be afecting my body. I also have a cyst on my left gland in my vagina. I have a docs app tommorow but I would like an Idea of what would be causing this today. thanks.