I hope you were able to get someone to drive you to your nearest emergency room? Please give an update?
There is no way to tell why your pressure was so high, that is a very dangerous blood pressure and you need to contact your primary care physician to discuss this issue.
Are you currently taking anything for hypertension?
If your whole body was shaking, so you think you were having a seizure? Blood pressure can increase significantly with a seizure. If this is the first time this has happened to you, I would strongly suggest calling your doctor today, or going into an urgent care to seek medical attention.
Best of luck to you.