Hallow Dear, If you were consuming Yaz pills regularly, you need not be worried about the unprotected intercourses you had since these pills are reliable birth control pills. If after the menses you have shifted from one brand to another brand of the pills, it is permissible and will give you protection form pregnancy. You have not mentioned which brand you have shifted to; hence I cannot know what are contents and the dosages of the contents in these pills. Some brownish to pinkish discharge you are having on yours panties is break through bleeding. If such bleeding becomes bothersome, you may take two pills on that day to stop the bleeding. Otherwise you may ignore it. Nauseating feeling you are having is due to increased acidity due to the hormones in the pills. Some proton pump inhibitor antacid like Pantoprazole will help you to get relief from nausea. I do not think, you need worry about it. If the new brand of pills is not suiting you, you may switch back to Yaz again after this menses. However, if you have any doubt about pregnancy, you may get pregnancy test done on the overnight first morning urine sample 8-10 days after missed period (if at all you miss). Earlier these tests may give false negative results. Alternatively you may opt for Beta hCG test which is very sensitive and gives you reliable results even few days before missing a period. I hope this helps you. Dr. Nishikant Shrotri