Don't try to go cold turkey from that level of coffee consumption, unless you're fine with severe headaches that no painkiller can treat and an inability to get out of bed. Buy 100mg caffeine pills so you can accurately control your caffeine dosage. Start the day with 100 to 200 mg, then later take 100mg only if you are having acute withdrawal symptoms (such as a vascular headache or severe anxiety). You should be able to get down to 100mg/day fairly quickly (a week or less?), after which you can either go cold turkey, or have one cup of black or green tea a day as needed.
This is not, technically medical advice, ask your primary care provider. This is just personal advice reflecting my personal experience.
You were right. Day two and I have a strong headache. If you didn't tell, I would not blame it is caffeine withdrawal symptom. I wouldn't believe it could have such an impact.
In the afternoon I went to pharmacist, but coffein pills are not on stock. Now, drinking strong Darjeeling with pain pill. Going to order pills online. Thanks for sharing.