What Causes Pregnancy Symptoms While On Mirena IUD?

I am sure you have been asked this a lot. I had the Mirena IUD inserted 10 months ago... but for the past 2 weeks or so i feel pregnant (cramps, bloated, nausea, tired, moody, dizzy spells, forgetful, very little spotting......) . I have two young kids and know how it feels. I don't want to go to my doctor and feel dumb by asking him. Just wondering if it really is possible that I could be pregnant and if it is really important for me to go to my doctor just in case.