DS had (many) temperature related seizures ("febrile"convulsionswhen he was little (18months to about 7ish). 15 mins was not too unusual. He also had a few after random minor injuries.
He then had prolonged periods of questionable consciousness 45 mins upwards that started late primary school. We eventually got a diagnosis for those too but its a fairly unique diagnosis so I wont share that one.
Its amazing what the body can withstand.
In both cases remember the first seizures/blackouts, the utter panic and being terrified. The feeling of not being able to go anywhere or do anything just in case. But that doesn't last. As time went on I knew what I needed to do, knew what signs I was looking out for and they became a part of life. You learn to live with a certain amount of risk and get quite quick at making risk assessments.
The "febrile" convulsions he did eventually grow out off (but I got very quick spotting a temperature or impending illness) and the others settled down with careful management and medication.
I wouldn't be surprised if they order an MRI and an EEG. They both seem scary but really done need to be a big deal. headphones, knowing what to expect and staying calm helps incredibly. You also might not get a diagnosis straight away. It's not unusual for a kid to have one seizure and never ever have another (DD at 6 months 
). If it does become a repeat event and if you have a few hospital visits, I found having a hospital grab bag with things like mobile phone charger, cup a soups , pass the pigs, colouring books and change of clothes for both of you incredibly handy. Hopefully that wont be necessary.
It's tough. But holding onto the good and fun things in life is really important