Copper t placed 8 months ago & had no problems .now spotting between periods , lower back ache. sudden weight gain 3 mos back.hormonal imbalance /iud?

Could be: The spotting between periods and low back ache could be due to the copper t having caused an infection. However, the IUD won't cause weight gain or a hormonal balance since it contains no hormones. The weight gain itself or the cause of the weight gain could be causing disturbances in your period. You need to see your PCP or GYN for a full history, exam, and appropriate testing. Hope this helps.