I felt a heavy pain in head after quite smoking about 3 weeks ago I m feeling it what should I do.?

How much Coffee? Smokers frequently combine that habit with heavy caffeine use. Abrupt decrease in caffeine can precipitate severe headaches in addition to the withdrawal of nicotine. Ex-smokers only need half as much caffeine to get the same effect, so you may be overdosing on caffeine if you consume the same amount as before and that can cause headaches. The cessation only headaches generally last about 14 days.
Smoking is addictive. And after quitting smoking people can have withdrawal symptoms in addition when people smoke they tends to drink more coffee and stopping coffee can cause ha, if u don't get better try to see your PCP for evaluation.