Pregnant while on IUD?

Me and my husband have unprotected sex at least 3-4 times a week, because I am on the marina IUD.

I was having some problems with my iud, some test, and some antibiotics for BV, and a vaginal ultrasound later I’m having some weird symptoms.

I had my vagina ultrasound June 8 and I was cramping and bleeding that day. Which I assumed was my period. Here we are and I’m supposed to start my period next week but for the past week or so I’ve had

-tender nipples

-I’ve had gagging episodes to breakfast sausage, tuna , and the taste of toothpaste

-diarrhea

I am a veterinary technician with military dogs so today back at work the dogs that have been coming in have been giving me an upset stomach

I thought maybe it was a bad stomach bug then thought it was covid but I’ve tested negative for covid and I took a pregnancy that may have been to soon. When I went to the Dr on the 8th the ultrasound showed no sign of pregnancy it was just to make sure my iud was in place , which they said it was. I’ve check for my strings lately and the seem a bit shorter but not sure if it’s because I have acrylic nails on that I can’t feel the strings…