Had a short, sharp reminder of how quickly things can change over the weekend.
Our son had had a pretty good day, a bit sleepy, but it was weekend and he is 27, so a bit of a lie in shouldn't be too worrying. Took him to a local event and had a pleasant chill out in the garden afterwards, and then some TV in the evening. Then late that evening, he had a major fit, not unusual, he went quite blue with it, again he does this sometimes, but we think he must have aspirated (breathed in some of his secretions) as his oxygen levels dropped through the floor. We spent the rest of the evening trying to get them back up and stabilised - we have an oxygen concentrator etc. We think he'd aspirated and the secretions were 'blocking off' a portion of his lung. He did settle to a reasonable level eventually, but it took some time as he didn't seem to want to cough properly. Kept him on oxygen overnight and he's been fine since.
Had to fend off all phone calls etc. so some people probably think we're a bit rude. It's times like this that remind us how fragile things can be.