Most probably Migraine
Thanks for the details.
From your details, I feel that the half headache could be due to Migraine as it reduces after going to bed.
Please see a Neurologist
who will start you on medications after examination.
Follow these instructions which will help in reducing your symptoms:
1. Avoid excessive glare, work on systems, watching TV for longer time, irritable smoke or smell. As these can be trigger points for your headache.
2. Whenever you sense you are going to have headache, go to a silent dark place where you can sit silently till the headache wanes off or if possible you can go to bed.
3. You can take a cup of coffee during headache, as its found to help in reducing headaches
4. Follow meditation
Hope this answers your query.