Why Am I Spotting Having Undergone Endoscopy For PCOS?

i have pcos and had operation endoscopy in july 2010 and from then i was medicine for 6 months and in december my course was over and my quite irregular with my periods i need to take medicine to start period jan2011 no periods took pregnancy test and it came negative and feb 2011 from 25th i started spotting in pinkish/reddish colour and today 28th it was brownish in colour