I strongly recommend that you go to see your primary care doctor
or your OB GYN doctor about this issue so that they can help you figure out what might be the cause of your menstrual irregularities.
It is certainly possible that you are starting to go through menopause a bit earlier than usual. Menopause brings with it irregular menstrual periods, which might include prolonged periods of light bleeding
like you are experiencing. It also, obviously, brings along hot flashes.
Another possibility, however, is that you are having menstrual irregularities and suppression from overtraining. In women who exercise excessively, this can be an issue, and it may be that there is a relationship between your intense training cycles and menstrual irregularities.
In addition to performing a complete examination, your doctor may want to draw some blood to perform some tests looking at your thyroid function and hormone levels. These results will help them figure out exactly what is going on and what, if anything, needs to be done at this point. If they find that your symptoms are being caused by your training, then you will need to back off on your intensity in order to help relieve your symptoms.