Thank you for asking Healthcare majic. My name is Dr Ehsan Ullah & I have gone through your query. well sudden onset and severe headache has got many causes like SAH,migraine,trigeminal neuralgia...As the history is not much clear i will like to suggest you to get visit as soon as possible to medical consultant to find out the underlying cause of your symptoms.. If this is worrying to you then definitely go to ER and seek medical advice for CT or MRI.. Meanwhile kindly get some pain killers and relaxing exercise should be learnt from psychologist...If you are having chronic headache this exercise will provide you much relief. Don t delay to visit your doctor. Hope this may help you. Let me know if anything not clear. Thanks.