Hello Doctor How To Know The Difference Between Normal Vomitting

Hello doctor
How to know the difference between normal vomitting and pregnancy vomitting? Iam 28 weeks pregnant and i vomit occassionally (previous three days i had vomitting during night only after 1 hour after my dinner).
This is my second pregnancy after 7 years . I have a boy aged 7. I had C section for my first child. I was in bedrest for the whole of my first pregnancy.
But this time doctor said that i can be normal this time.

Please clarify my doubt regarding my vomitting. My scan and othet tests are normal.