What Causes Headache And Belching?

i went 4 my exam since then m suffering from headache.i thought it was due to my eyes,i consult an optomologist,my eyes are perfect6/6.he has given me gas tablet ans pain tablet.i m bit ok,but i feel pain.on other hand i belch alot..my stomach is full of gas and incresed in size abit. i dont want to take any medicine,coz medicine also causes acidit.neither i eat outside,nor i use any thing which cause belching.