I've had asthma my whole life, my sister too, I remember my Mum reading me a few books about asthma, and Dad making calling the nebulizer mask the spaceship mask and making whooshing noises while I was on it, so while asthma was scary it wasn't so bad, lol.

I dont remember anything about ventolin and the runs. Ventolin makes your heart race a bit and you feel a bit shaky, so keep an eye on him when he starts getting back to normal. I remember feeling very tired after an attack, and I tended to cough a lot before them (some people just wheeze) so I was exhausted from the coughing as well. I also remember my Mum trying to convince me not to run around the day/few hours after an attack, it was very hard to keep still when you were feeling ok again!

I'd still give ventolin every 4 hours, but that's just me. Good luck, I know it's scary!