Wow! You must have been in a very bad accident. It is exceedingly rare to herniate all of those discs. I'm sorry.
Anti-depressants can reduce pain by inhibiting the reuptake of bloodstream Seratonin. I would take this as an axiom. However, if you have moderate to severe pain, it likely would not be up to the task. Paxil is an older but widely used anti-depressant. There are few major side effects.
Neurontin is also not a pain medication. It's an anti-convulsant with some efficacy for neuropathic pain. If you have nerve-related pain (pain that transitions down a leg or into a hip), then it might help. Klonopin is also an anti-convulsant. You must never take these drugs together.
Zanaflex is a muscle relaxer. It is not a pain medication.
Ironically, "zenjan," you are not taking ANY pain medication, except the very mild pain reliever, "Norco." That is strange for someone with chronic pain. Have you asked your doctor why he or she has not prescribed a decent-strength pain medication? Most chronic pain patients respond much better to using a long-acting opiate (Kadian, Oxycontin, Fentanyl Transdermal, etc.). Then, if you still have breakthrough pain, you can use it in addition to the long-acting drug.
If you are also in a pain management program, you should try each of the following options:
a corset, brace, TENS, traction, acupuncture, biofeedback, physical therapy, kinesiotherapy, injection of steroids and anesthetics, non-steroidal anti-inflammatories, cortisone, rhyzotomy (radio frequency denervation), spinal cord stimulator, intrathecal infusion pump, off-label medications (anti-depressants, anti-convulsants), combination of long-acting pain medication with breakthrough meds, counseling, hypnosis and meditation. I can reduce my pain by at least 20% with biofeedback alone. That's in ADDITION to using your pain medication and other off-label drugs. In fact, if one or two of these options works well, you won't need as much pain medication.
Good luck.