18 weeks I have a headache but I don't understand if it's spinning. As…

18 weeks I have a headache but I don't understand if it's spinning. As far as I understand when the head spins, it gets dark in my eyes. But I can't figure out if it's spinning or not, just like something is pressing on my head and there's this feeling that it's spinning, but it doesn't get dark. I hope you understood me.