Consider looking into Lyme disease. The intense meningitis I had and long term side effects ended up being caused by a co-infection to Lyme, Ehrlichia Chaffeenosis or Human monocytic ehrlichia from a tick bite. I did not remember a tick bite or a rash which is consistent with 50% of patients. Many of my neurologic symptoms have disappeared with long term antibiotics and supplements.
You have to go to a Lyme specialist for the right testing as most of the common tests the doctors order are not accurate enough. I continually test negative for Lyme disease but positive for the co-infection, (having a negative test result is common). You have to test with one of the three recommended labs that the specialists refer to. Lyme borrelia can cause similar symptoms and is caused by a bacterial spirochete.
If you continually get migraines, there are some medications that can help so keep asking and seeking a doctor who is compassionate.
My original doctor said that once you get meningitis, you are more susceptible to getting it again. I would keep looking for answers if you are getting it often like some of the replies above. Best wishes.