Could a possible miscarriage be why my lower back is still hurting pretty bad?

If...: If you are certain of being pregnant( have had a positive pregnancy test) and having vaginal bleeding this could be a miscarriage or danger of having one. If this is the case go and see your gynecologist as soon as possible.

Back pain: There are many causes of back pain from muscle strain to nerve impigment. A miscarriage possibly could be in the differential diagnosis if associated with pelvic cramping and bleeding. This would be very concerning to me and I would recommend immediate evaluation.