I have recently watched two plays that had strobe lighting and have had a rather alarming reaction to them. I feel very faint, my heart rate increases at an alarming rate, I get extremely nauseous and afterwards have a bad headache that lasts for several hours. I also had the same reaction whilst watching a movie that had strobe lighting in it. I am extremely concerned about this as I have previously been around flashing and strobe lights with no issue. Could I have developed a sensitivity or even epilepsy? What could cause a sudden change of reaction? I am making an appointment with my doctor ASAP as I've heard this is what you should do if you develop a sensitivity but would just like some idea of why this is happening.