I have a dull, increasing pain, on the lower right side of my lower back. It is right between my spin and my hip what could this be?

Several possibilitie. In that region, pain can arise from a hip, spine or si joint problem. It can also be a referred pain from your abdominal or pelvic region organs as well . If the pain is getting worse or persisting over time and is bothering you, get evaluated by your doctor to start the appropriate treatment based on a correct diagnosis.