Hi Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concern...
Irregular periods can be because of many reasons. It can be related to getting pregnancy if you had
unprotected intercourse since your last period. In that case you should do a pregnancy test first.
However the last bleeding you had should be your period & not
implantation bleeding as it was heavy & lasted 5 days. Implantation bleeding is light & lasts for 2-3 days maximum.
Irregular period are not because of any seasonal variation & Other reasons that can be responsible for irregular periods are mentioned below:-
1 Poly cystic ovary disorder- It is very common disease. In this ovary of patient becomes segmented & cystic & patient can have
irregular menstruation. It can be easily diagnosed by an ultrasound.
2
Excessive weight gain or weight loss can cause changes in your pereiods
3 Hormonal disease like thyroid can cause irregular periods
4 Over exercising as in sports persons, athletes can also cause irregular periods
Refer to a gynaecologist
Hope this information helps