It is definitely not Tarlov cysts, which are cysts of the nerve root. The main symptoms of this condition are:
Pain in the area of the nerves affected by the cysts, especially the buttocks
Weakness of muscles
Difficulty sitting for prolonged periods
Loss of sensation on the skin
Loss of reflexes
Changes in bowel function, such as constipation
Changes in bladder function, including increased frequency or incontinence
Changes in sexual function
Do you have a fever? Blood infection would almost always cause a fever. If you do not have a fever, then it is not a blood infection. My guess is that your cat bite 15 years ago is not related to all your conditions.