welcome to the forum,
thanks for consulting,
spotting at the peri menopausal age is a bad symptom,
you should visit a gynac and get yourself investigated . you need to do a pap smear
to see for infection or any epithelial changes towards CIN or squamous cell carcinoma
get an ultrasound
done as well .
the symptom of lower back pain could be due to pelvic inflammatory disease
(PID), which can be rules out by ultrasound.
do visit the doctor soon.