Hi and welcome,
What you are describing sounds suggestive-consistent with 'Sciatic' nerve involvement and it's highly doubtful you have sustained anything like a permanent spinal injury and or or nerve damage when your spinal MRI hasn't shown any of the expected structural spinal explanations and your EMG is showing you don't have any peripheral nerve damage...
"Sciatica Nerve Pain
Sciatica is often characterized by one or more of the following symptoms:
Constant pain in only one side of the buttock or leg (rarely in both legs)
Pain that is worse when sitting
Leg pain that is often described as burning, tingling, or searing (versus a dull ache)
Weakness, numbness, or difficulty moving the leg, foot, and/or toes
A sharp pain that may make it difficult to stand up or walk
Pain that radiates down the leg and possibly into the foot and toes (it rarely occurs only in the foot)
Sciatic pain can vary from infrequent and irritating to constant and incapacitating. Symptoms are usually based on the location of the pinched nerve."
It's possible what's causing this is muscle related if other common causes have been ruled out...
Piriformis syndrome is named for the piriformis muscle and the pain caused when the muscle irritates the sciatic nerve. The piriformis muscle is located in the lower part of the spine, connects to the thighbone, and assists in hip rotation. The sciatic nerve runs beneath the piriformis muscle. Piriformis syndrome develops when muscle spasms develop in the piriformis muscle thereby compressing the sciatic nerve. It may be difficult to diagnose and treat due to the lack of x-ray or magnetic resonance imaging (MRI) findings."https://www.spineuniverse.com/conditions/sciatica/6-leading-causes-sciatica
...i think it might be helpful for you to see a physio therapist and get an assessment, learn all tips and tricks eg stretching and strengthening exercises etc that might be necessary to aid in your recovery.
Hope that helps......JJ