What is going on?!!

So I’ve had the Mirena IUD for about 2 years now. For the past year or so I’ve been having a normal (regular flow, no crazy cramping, 5-6 days) period but about every 2.5 weeks. The month of June I was late by almost 2 weeks but didn’t think much of it. My period lasted 16 days with 3 days of spotting prior to a regular flow. It ended on the 30th and for the last 3 days I’ve been spotting with clear discharge. I’ve had a lot of headaches, nausea, some dizziness today, feeling really fatigued, constipation, and restless sleeping due. pregnancy test? Something else? I’m not convinced that I could be pregnant since I have my IUD. Thoughts?