I have never had a problem with acne. i have always gotten 1 pimple at a time maybe 3 times a year. lately, i have been getting 5-6 at a time. why?

Don't ask why: You probably will never figure out why. Acne comes and goes unpredictably and if your periods are still regular and there's no big change in your diet / lifestyle, a search is futile. The key is to start managing your illness more aggressively. A salicylic acid wash or topical benzoyl peroxide as tolerated may be enough to keep things under control.