Hi, and thanks for your query on eHealth forum!
HPV can be a cause of spotting and brownish discharge between periods. It can also be due to precancerous or cancerous lesions in cervix as HPV is a strong risk factor for cervical cancer. Hence a PAP smear is a must.
There are many other causes of spotting between periods such as hypothyroidism, cervical polyps, cervicitis (infection/inflammation of cervix), vaginitis (infection/inflammation of vagina), uterine cancer, uterine fibroids, hormonal imbalance as in polycystic disease of the ovary, use of blood thinners, genital ulcers, STDs and stress.
I think you should discuss these possibilities with your gynecologist. A comprehensive investigation is required keeping all the points in mind. Hope this helps. Take care!