First, you should see your primary care physician. He/she will decide if you need a referral to a specialist.
Second, consider your most conservative treatment options, such as medication and Physical Therapy (PT). There are several types of Physical Therapy options. If you have seen a Physical Therapist before and still have chronic back pain, maybe you need to find a therapist that specializes in the spine.
There are three main forms of specialty PT that are most effective for chronic back pain. Mechanical Diagnosis and Therapy (MDT), Manual Therapy, and Aquatic Therapy. Your primary doctor, spine specialist or pain specialist may prescribe PT for you and refer you to a specific PT clinic. But do not hesitate to do your own research on local PTs in order to find the clinic that will best meet your needs. It is your choice where to get your Physical Therapy once it is prescribed (just like you choose your pharmacy). Just remember that not all PTs are the same. Some clinics specialize in orthopedic rehab, neurological rehab, pediatric rehab, spine rehab, aquatic therapy, geriatrics, etc, so select carefully in order to maximize your time, effort and cost. Getting the proper Physical Therapy could help you to prevent injections or even surgery.
Third, if you are still not getting better, follow up with your doctor/specialist. You may be a candidate for injections or other treatments. Injections are effective for some back patients. Some get short-term relief, some get long-term relief and some get no relief, depending on your diagnosis and other factors.
Fourth, increase your fitness level. Get on a weight loss program if you are overweight or obese. Start exercising regularly. This, by itself, could drastically decrease your back pain. It is urgent that you start to do cardio exercise 5-7x per week. Work up to at least 30 minutes per day of moderate to heavy cardio exercise (a walking program may be the easiest, cheapest and most convenient option).
Fifth, if you have done all of the above and still have chronic back pain, see your specialist again, or get a second or third opinion. You should at least know your diagnosis, prognosis and treatment options. If you do not know these yet, ask more questions until you get the answers you seek.
As a PT, I obviously recommend PT over other treatment options. I recently saw a patient with chronic back pain for >20 years and radiating leg pain for >1 year. Within 1 PT session his leg pain was gone and within 3-5 sessions, his back pain was gone! A PT will help to find the cause of your pain, the proper treatment(s), and the best ways to prevent future episodes.