You have options and ending your career is not necessarily a requirement. When I first knowingly started having seizures and reported them. I was only asked to keep the Navy updated and depending on frequency and level or degree of severity would make a huge difference in what could be offered to continue my military career.
With only one reported seizure and no actual diagnosis they only asked I report back if changes occurred or if within 6 months more seizures had occurred. First time around I was cleared and it was around 3 years before I experienced another seizure. Still not diagnosed, but my seizures now come with frequency and actually affect my working abilities.
The second seizure event only prompted the Navy to give me the same spill as the first time around. The 3rd seizure event only 2 months later prompted my chain of command to help me look for some options. My first request was a 6 month leave of absence, but unfortunately before it was finalized... My 4th seizure event occurred on base and it gained a little too much attention.
In conclusion, I must pay back the prorated portion of my enlistment bonus, I lose partial college funding, must pay for my own medical insurance now, I lose my SGLI and was transferred to the IRR just this Sunday, but I too was thinking exactly like you until I was able to get all the answers from some savy friends like my CO, CMC, HMC, Chaps and CCC. It took us 2 months to get the first response, and a combined total of 6 months to find a suitable answer since my medical condition rapidly went downhill; but, I have 5 years to recover with annual medical review boards to find a sustainable solution and if I do, I can return to active duty.
Not the greatest thing to hear, but it was huge relief to me once I received a final answer. The military is truly the only job where I have actively enjoyed my life and career. If you are able to request the IRR before going in front of a medical review board or having the seizure disorder permanently in your record you can avoid the 5 yr limitation in writing. Even still, I'm not sure I would avoid limiting myself to 5 yrs without a seizure before going back considering my 3 year time gap between seizure #1 and #2.
Depending on how important it is for you to return to service... You may also want to know that if you were diagnosed while in the service and/or can prove that it is military related, you will likely be discharged with 100% disability. If I remember correctly the type of seizure disorder can affect % amount. Check the VA website for more information or even better talk to your local VA Assoc, that assists vets in receiving VA benefits, first one that comes to mind is Purple Heart Assoc but there many.
