Medication for pain relief is certainly necessary at times to make it through the day. If you have an injury and medication removes the pain then you have no way of knowing if your activities are aggravating your injury. Pain is your body’s cry for help. It is important to identify and treat the cause of the pain so that the injury can heal properly. Otherwise that pain continues to return and you end up taking medication for months if not years. Most sprain / strain injuries with heal within 6-8 weeks. If you haven’t had any therapy and your pain is still requiring medication one month after your injury then you will need some form of physical therapy to resolve your injury properly. Most injuries will require treatment to achieve maximum healing.
It is difficult to give advice without a thorough medical history and physical examination however based on your report I would not advise trying to straighten your spine or stretching it. The most likely cause of your pain is either acute inflammation of the facet joints in your lower lumbar spine or you have a disc bulge in your lower lumbar spine. Your pain is not likely to be muscular as it hurts to bend backwards. There are no back muscles that pull when you bend backwards. You are therefore compressing some swelling from an inflammatory process in the lower back and this is causing your “electric-shock like spasm”. You would be best to put some ice on your lower back (for 10minutes at a time, but not directly on your skin) to reduce any inflammation that you can, and get some chiropractic therapy to correct the dysfunction in your lumbar spine. As you have only had the pain since this morning and there is no pain in your legs, your symptoms should resolve quickly if you don’t delay getting treatment.
I can’t stress this enough. Most lower back pain will be the result of joint pain. This will be in the form of joint inflammation and joint restriction. Getting massage therapy or doing exercises and stretching may be great for peripheral pain syndromes (pain in the arms and legs) but they are fairly ineffective when it comes to treating lower back pain. Treating lower back pain with massage, stretching and exercises may provide temporary relief but as there is no treatment to the joints of the spine the pain will always return. Chiropractic manipulation is the most effective form of therapy for lower back pain as manipulation is the only physical therapy directed at the joints of the spine. When treating lower back pain my approach is to spend the first few sessions just doing manipulation. This will tend to eliminate most if not all of the pain. Massage, stretching and giving exercises can then be given to support and enhance a well functioning spine. I hope that has clarified things for you.