In my opinion, these symptoms are concerning for some type of neurological condition, so I recommend that you speak with a neurologist
. The back pain could be due to many different causes and might not be related. The most significant symptoms you describe are the phantom smells and the twitching. These symptoms could be very indicative of seizures
. Seizure activity is often preceded by phantom smells often something similar to rubber burning. The twitching could be a sign of complex partial seizures which would accompany the smells as well. The burning in the legs could be related or unrelated to the twitching and the smells but definitely could be related to the back pain. Low back pain due to spinal stenosis or other causes of a pinched nerve could cause a burning sensation the leg along with back pain. For these reasons, I suggest that you schedule an appointment with a neurologist. A neurologist will be best equipped to put your symptoms together under one diagnoses as possible. An MRI
of the lumbar spine and an MRI of the brain will likely be diagnostic testing that is necessary to determine what is going on. An EEG will be necessary to tell if you are having seizures, if the neurologist is concerned about this possibility. Good luck.