Can anyone help please

HI
I had a merina coil fitted after my last child was born and had no problems.
then i had it replaced started having pelvic infections had the coil checked it was ok was given anti biotics thought that would be it , then suffered heavy discharge thought it was from the Antibiotics got treated but i carried on getting heavy discharge with a regular period mixed in, whent back to the doctor where to my embarrasement got checked for stds which came back negative, the discharge is getting worse more than a period and i blame my weight gain to myself but my increase in bra size from a 32 dd to a 32 g i cannot explain iam so depressed i dont know what to do for the best i have had the new coil for more than a year i thought it would settle are these symptoms usual or am i being paranoid any help would be very much appreciated x x x