Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with a doctor.
Without the ability to examine and obtain a history, I can not tell you what the exact cause of the symptoms is. However I will try to provide you with some useful information.
First time seizure can be concerning. It is important to accurately describe the seizure, timing of the day the seizure occurred and also in what setting. Then the question arises if the seizure should be treated – this is answered by looking at the risk and benefits of having a recurrent seizure and the side effects of the antiepileptics.
Ultimately, the workup will need to identify the cause of the seizure. Is it from an intracranial lesion, an epileptic syndrome, stress, etc? You will need to have neuroimaging performed (i.e,. an MRI of the brain), and likely an EEG to identify focality (either a short-term EEG or prolonged/overnight EEG).
I agree that you need to follow up with a neurologist. The chances of seizure recurrence will predominantly depend on the underlying etiology.
Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.
There are drugs that can cause seizures. Since you are so young and have not had a head injury of any type that would be something that I would think of. My son had a couple of seizures before he quit taking drugs that he should not have been taking. It scared him. He did not like the seizures. They are scary. If you have done nothing like he did then the neurologist will really be able to help you. Try not to worry until you have some answers. I know that is a hard thing to do.