The Chiari I malformation is fairly common. Many individuals have these malformations and have no neurologic symptoms. Therefore, it becomes important to ensure that no other problems are occuring. Some of the symptoms you described could be caused by a Chiari malformation. Lumbar punctures can be performed in patients with these malformations as long as they are not severe. Therefore, I would have to see your films prior to determining if you could have a LP.
I am assuming that the remainder of your brain scan was normal. You stated that your CRP level is elavated. I assume other markers such as ESR, ANA, ACE, and RF have been checked, and are normal. Also, have you had a MRI of your cervical spine.
You should ask your neurologist and neurosurgeon if other disorders have been completed excluded, and is the chiari severe enough to cause your symptoms. If you are not satisfied with this evaluation, a second opinion with another neurologist would be appropriate.