For neurologic symptoms (insomnia, too frequent headaches, stiff painful neck, weakness of legs/arms), definitely get a doctor look at neurotropic latent viruses (IgG and IgM antibodies in blood), especially the herpes family viruses, with which almost everybody is infected. These can wreak havoc on the brain and spinal cord if they get in the CNS: Herpes Simplex 1 or 2, Varicella Zoster (Chicken Pox), CMB, Epstein Bar (Mononucleosis).
Also check Measles (Rubeola) IgG and IgM. It is in the MMR vaccine and rarely can mutate and go nuts on the CNS.
There are recent studies that Alzheimer might be caused by Varicella virus activating, which in turns activates Herpes Simplex 1 in the brain leading to brain inflammation, destruction of neurons by the immune system, and deposition of plaques that are observed in Alzheimer.