What Causes Motion Sickness And Nausea After Taking Depo Shot?

I am on the depo birth control shot. I got my last shot about three weeks ago and it was my 3rd time getting the shot. A few days before I got the shot (I got it a week late too but dr said not to worry) I started to feel almost car sick at night. After I got the shot I started feeling car sick in the morning, extremely nauseated and dizzy but haven't vomited. Its like a lump in my throat. Food helps sometimes other times it makes it so much worse. It lasts for about 3-6 hours every single day for three weeks now whenever I wake up whether its from a full night of sleeping or a nap. Could I be pregnant? I have taken three at home pregnancy tests all neg in the past week but I have two fam members who didnt have positive urine pt results until 2-3mo :/