First of all, keep in mind that I am unable to diagnose you because I am unable to examine you, this forum is for educational purposes.
The pain in your left calf and subsequent back pain may be due to a pinched or irritated nerve (pain from a L5/S1 nerve root would be felt or 'referred' to the calf area). When there is an annular tear then some disc components can leak out and either compress or irritate the nerves. Many people without out any back pain can have findings of annular tears, compressed discs and bulging discs on MRI. Thus it is unclear who will have diabling pain just from an MRI. I would suggest an EMG of the left lower extremity to evaluate for signs of radiulopathy (damaged nerve root). Conservative therapy with physical therapy, pain medications (NSAIDS and sometimes narcotics) along with epidural steroid injections are usually preferred for the first line of treatment. If after 6 months of conservative management, you are still having significant pain, and functional limitation then you should see a surgeon, neurosurgeon or orthopedic spine surgeon for possible disc fusion surgery.
I hope this has been helpful.
had the same thing. if your problem is like mine, youve got muscle spasm/trigger points. you need a qualified expereinced trigger point therapist (or get the trigger point manual by Clair Davies and fix this yourself). I doubt you MRI reading/findings have anything to do with your symptoms. all your muscles are connected. If you develop a spasm in one place (calf for instance) muscles in other places will try to compensate to keep your musculature in balance. there are specific exercises and stretches for low back pain-- see a website by Jolie Bookspan. Your calf should be treated often w trigger point therapy to break apart the trigger point. I saw a therapist in chicago named Sharon Sauer (Myopain.com). she was the assisstant for Janet travell, who has passed on, who wrote the book on muscle pain.