I have been on the pill for years now and have taken correlcty, eveyday around the same time. My period has not come this month and they always come on time. I have not any sexual intercourse since my last period. Since my last period i have had an coloscopy and have starting taking antibotics for my Thyroid Glands as they are inflammed. I am i pregant or could the antiboticis be affected my periods??? I have being getting PMS and period pain just like a normal would do aswell. PLEASE HELP!!