welcome to HealthcareMagic
The spotting is due to hormonal
imbalance;polyp;submucus fibroid;cervical erosion etc for which you need to consult a Gynaecologist for examination and treatment.As for low back pain
it can be due to or related to spotting.The headache may be due t excess work fatigue;sunstroke;sinusitis
etc.Better get examined and treated for spotting and for headache you can take a painkiller.