gastropresis slow stomach and stomach pains

for the pass 2 years i been suffering from stomach pains.i went to 4 different gastro spc and all dod  EGD and pretty much they said i had gastritis and one doctor said i had slow stomach.but i try many anti acid medications and none seems to work for me.i also started to get headaches every day for a few months now i done a mri and ct scan and both were normal and i had blood drawn and that was fine.so  i dont know whats happening to me.iam going back next week to do another gastric empty test for the slow stomach to see if its really that and if its bad.i try domperidone for a few weeks before and it didnt work but iam willing to give it a try.maybe i wasnt taking it right,my question is how do you supposed to take  domperidone do you take 30 minutes before you eat or what,cause i just took it up when i got up in the morning and half of day and when i get home from work.my question is do u supposed to take this medication before you eat.