What Causes Light-headedness, Headache And Blurred Eyes?

The last 3-4 weeks I ve been feeling really lightheaded like a few times each day and when talking to my friend about it she said that s how she knew she was pregnant. I m on the Cerazete Pill which I was on for a year and stopped my periods and came off it and am now back on, have been for 6-12 months and I was still having periods, the month before last, I was on for a day, not very heavy at all and last month It was as if I was coming on but never did and this month I ve had nothing and am 2 weeks late. I ve been having loads of headaches lately, I get them usually but nothing like lately since I ve been feeling light headed and today my eyes are a little blurred so just wondered if it sounds like a pregnancy or if its something else. thanks for you help.