Doc gud morning ....Why if I feel hungry my head...

what is the cause of headache in your case ?
hunger cause headache as body muscles tighting up specially neck and head muscles , as well as low blood sugar lead to such a symptoms 
how to prevent it ?
prevent hunger 
general advices :
1. dont take medications to treat headache , eat first , then if the headache lasts more than 2 hours , take ibuprofen and work on preventing it in the future 
2. if your appitite isnt that good , no need to have heavy meals every time , but you should get snacks every now and then during your day to prevent it 
drinks to help with headache :
1. herbal tea 
2. ginger 
other advices :
1. avoid stress and anxeity sources 
2. stop taking any medication that causes headache as a side effect 
3. stop using any high brightness screens such as phones and laptops 
4. have a rest and avoid over load physical stress
5. avoid smoking if you are a smoker