IUD removed

So I had my IUD removed almost four weeks ago. I had what felt like a 4 day period a couple days later, but I assumed it was just bleeding from the removal.

I'm now experiencing a lot of nausea/vomiting and stomach cramps every night at work. I have times during the day I feel fine. Am I experiencing hormonal withdrawal? I don't know when I'm going to have a normal period again... would it be worth a pregnancy test already? My friend is a women's health nurse and says there is slight chance I could already be pregnant. I just don't know when I should test.