Looking for info

Hi, I'm new to this site and just a father looking for answers. Recently my 15 year old son had his first seizure doing a workout for football at his high school. At first the Amubulance and ER doctors waived it has a heat stroke or dehydration, which honestly was eaiser to accept. A month later he had another one in the weight room. We took him to a pediatrician neurologist who put him on kepra and did an extensive amount of tests. He has had an EEG, a stress test, MRI, blood work and physical. He has played football for four years and has since then had to quit for obvious reasons. He has never had a head injury or any for that matter. He's a great kid with straight A's. All the tests came back negative and they told us physically he is a healthy 15 year old. We thought it was behind us and recently he had two seizures in the same day since his last one 3 months ago. This was our first time experiencing this since his first two seizures were at the high school. This shook us up. All his seizures last for about a minute. His eyes roll back and foaming at the mouth. Once they stop it takes him about 20-30 minutes to recover and realize what's going on. We took him to the ER and they did all the test and once again nothing. It's frustrating not knowing what causes this or will he be ok. We are always worried and hoping for answers. We have an appointment with the specialist and are hoping for some kind of news or answers. At first I thought it had to do with him working out but the last two that he had in one day was in the backseat of our car and in a restaurant. This has me more lost than ever. If anyone has any ideas or suggestions I would appreciate it. Just a concerned parent. Thanks.