Is Paragard Or Any Other Problem That Caused Infertility?

I am 19 years old i gave birth to a beautiful healthy baby boy on 3/31/09. almost 8 months later i had paragard put in till i was ready to have another baby. right away something went wrong, i had extreme pain and horrible bleeding. the doctor removed it and my periods were still very irregular and heavier then a normal heavy flow. I went back to the doctor and told him i was ready to concieve again and would like a check up. he did lots of tests and blood work ad told me that would be a problem because i hadnt ovulated. i repeated that ovulation blood test for several weeks and concluded that i had not ovulated at all. i am infertile after having paragard put in and removed. My question is this. When i ask my doctor why it is that i went from being able to get pregnant 2 times in six months to being infertile after pargard. his answer is i dont know. i tried fertility medications that failed to make me ovulate. i cant aford anything else. and paragard does not state infertility in the warnings other then if you have PID which i do not. why am i infertile? was it paragard? or an underlying problem my doctor is not seeing?