What Causes Spotting During Menstruation And Weight Gain?

I skimmed my periods February and March. i usually go on for 5-6day on the 8th or 9th of every month. I was scared that i would miss again in april but i started (spotting) from 11 april upto today 26 april. The flow is very light and most of the time nothing comes out which is not normal. I am really concerned because of the lenghth of time. I need to travel out of the county on thursday night and really dont want this to continue. I am not pregnant (have not been involved in sexual activities)but have gained weight these past months. What can i do. I am also having minor boils. what is causing these kinds of changes in my body. I am 26 and now weigh 69 from 60. I am have started dieting and hoping to reduce my weight. Please help