What Causes Vomiting Post Food Intake With HPT Negative?

Hello. I am a married women. I have irregular periods. We are planning for a baby and 2 weeks after our first try, I started vomiting after having my food. I consulted gynaecologist and she did scan and blood test for pregnancy, the results came negative and she told that the reason for vomiting is delayed period. After two weeks of consultation I got my periods naturally. Now again I started vommitng early in the morning and after having food. What will be the reason.