What To Do For Irregular Periods?

Hi. I have been having a very irregular mentrual cycle. I have had my period for the past two months, at every alternate week or so, meaning that I've got it for 6 weeks or so in the past two months. Prior to that I did not get my period for 3 months. Prior to that I had my period for 2 months, prior to which I did not get my period for 3 months.

This apart, there has been sudden weight gain and now in the past one month relative loss in weight. Noticable increase in facial hair also. Is there something to worry, or is it stress induced hormonal imbalance?