I'm not sure what's wrong and what I should do

I have had an IUD since the beginning of November and gotten a period each month, this month it was late by 4 days and now it’s so light I almost don’t need a pad.
I have nausea the past 2 weeks, which doctors thought was due to meds but those have been changed and it’s still not going away.
I took 2 pregnancy tests that were both negative.
I have also had pain in these spots (purple spots in picture) and my lower back.
is this normal? if not what could it be?image

are you overweight? possibly ovulation didn’t happen
you should be fine by this time now?