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If you had periods for 10 days and still if you are spotting have pain in back then it is better to consult a Gynaecologist and get examined and treated.With out examination it will be difficult to just prescribe medicines in your case.As for the back pain
to get a temporary relief you can take a painkiller like paracetamol
or a combiflam
if you are not asthmatic or allergic.