Change in nausea

Throughout week 6 of my pregnancy I had moderate nausea with no actual vomiting, just dry heaving. On Saturday it was so bad that I barely got off the couch. Today, (7 weeks 2days) I had barely any nausea, but dizziness and headaches. Does this mean something went wrong? Or is it normal for a change in nausea symptoms from week to week? Has anyone else experienced something like this?