well excessive training and hardwork can impart severe stress
on your cycles leading to early and scanty menses n form of spotting. this is called polyhypomenorrhoea. i suggest you take tab tranexamic acid
500mgtwice a day for 3 days to stop the bleeding and maintain a menstrual calendar for next 3 months counting this spotting as the onset of your fresh periods. with the calendar the changed pattern of your cycles can be well evaluated under your stressful conditions and can be advised accordingly.