Every time I smoke lately, I feel lightheaded and my knees go weak. I ve been smoking for 14 years, and this only started 2 weeks ago. I also have recurrent migraines and headaches, the first on the left side of the head, starting from my eye and going back, the second starting from the back of my head and spreading. Sometimes my vision gets blurred, even though opthalmologist finds nothing wrong with me, and I have a severe aversion to bright lights. I generally have low BP and my blood tests came back normal. Any clue what might be wrong ?