parasites in the brain symptoms are usually loss of function or sensations in other parts of the body as there are no pain receptors in the brain. So pain would be due to some disturbance outside the skull.
There are several herbs that increase circulation to the eyes and brain - eyebright, gingko biloba so that supplements and parasite herbs might be more effective.
Two signs of zinc deficciency are cracked skin on heels and white spots under fingernails. I keep taking zinc until my heels are smooth and white spots stop appearing.
parasite herbs used with a Clark's Zapper or Rife device are more effective.
Doing cleanses and detoxifications to clear the body of pollutants often eliminates 'floaters' in the eyes.