Welcome to HCM,
It seems that you might be having some infection in your Genito-urinary tract giving rise to this problem.
Go for routine urine check up for bacteria, blood to rule out urinary tract infection
or calculus in kidney
There might be some problem with IUD as well in relation with infection, changed IUD position etc.
Go for ultra sound
Consult Gynaec and she may go for above mentioned investigations.
Ok and bye.