Hello,
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Since you are in perimenopausal stage it is common to have irregular bleeding with spotting.But itching along with back pain might be due to infection which can be due to yeast or bacteria,pelvic inflammatory disease,endometritis,polyps,cervical dysplasia etc.
Even after taking antifungal medications the infection seems to be there.
Wash the area twice with antibacterial soap and water.
Avoid wearing tight undies.
You can also wash the area after mixing tea tree oil in water.
You require a pelvic examination and Pap smear test.Kindly visit a Gynaeologist for evaluation.
Take Care!