Hello! You are obviously stressed out cause of your exams. Please try to understand that 6-8 hours sleep is essential every night for registering all that you have learned into your brain. There is no quick fix to your sleep problem. Some tips you can follow is stop taking coffee, and don't try too hard to sleep. If you are not getting sleep, you should do some reading and wait until you again feel sleepy. A warm bath can help you feel sleepy. You can take paracetamol
for your headache.
Hope I am able to solve your concerns.