lingering tummy bugs, teething, night time changing

[fruitstick]

DS2 is 9 months and had a tummy bug 2 weeks ago.

He's no longer being sick and has his appetite back but his nappies still smell like a sewer and are very snotty/runny.

Worse of all, he keeps pooing at 3am and needs changing. Quite often babygrow, sleeping bag and all.

He's also teething.

How long do bugs go on for?
Will he eventually stop pooing in the night?

Another 4am nappy change. His food seems to be going straight through him - it looks exactly as it did when it went in

What can I feed him to slow his digestion down a little (well, 3 hours to be precise)