It may be effects of the pill, if your on the pill it MAY not be likely that your pregnant - they are normally 99% effective if not more. If your concerned you may be pregnant then run a test when your next cycle is or would be due, if you dont want to do one at home then go to your doctors and they will do one for you, they have a confidentiality policy and can not tell anyone why you were there. Good Luck to you