Actually, medicine, the modern medicine has not found a single cause for why it happens, but obviously, if the woman is going through changes every month, sometimes it could be internal factors or external factors, but I would personally go with an internal factor, which could be stress non-acceptance of your own self, thought processes, which, are not harmonious between various organs.
These are compounded further, so the root may be there, but later on, there could be an asymptomatic relationship between increased pollution, as they say, increased sugar intake. Maybe pesticide driven food. So we don’t know exactly what causes it, but fundamentally any issue that a person faces.
So if I face any issue, it has to be, there has to be an internal weakness. So if there is an internal imbalance, which could be basically driven by the mind or the thought process could result in this.