Irregular Periods

I am 5'4" and weigh 47kgs, 22 years old and unmarried. I used to have a regular cycle of 28 days. Since May 2017 my cycle has become quite irregular, varying from 27 days to 47 days. I experience leukorrhia, always of whitish color or transparent, and my periods become rather sticky on last day. I have always suffered from constipation. What should i do to make my cycle regular again? Do I need to see a doctor?