Twisted, how stressy and dreadful for you.
Most people will tell you to drop the milk as it feeds the bugs. It is very possible that after a tummy bug a baby can become lactose intolerant. A very helpful MNer told me this the other day as my DD seems to get this everytime she has a bug.
Last Feb we have a week of sickness and I was told to give DD cold, flat, fat coke to drink. Apparently it settles the tum and can help give them the sugars and salts they need to fight the bugs. It was so strange, I would never ever give a child coke but oddly it did work. We hit a turning point and then she rebuilt.
Other things you can try are a prebiotic (acidophilus etc) which is powedered and it helps to rebuild the stomach on bowel bacteria.
I think all the non-lactose baby milks are on prescription, my friends DD is daily intol and her milk can on prescription - have you been to a doc?
The other thing which is almost impossible is to do a 24 hour milk starve, just water but I know you will say you will end up with a sreaming baby.
NHS direct told me to never ever give more than 2-3 ozs with a bug. Little and often and let if digest before adding more. They do get quite desperate but it does help.
Was also told by a paed GP (sorry, I am really rambling now) that yogurt can help if you 'water' it down with milk and feed off a spoon. We did this too and she did keep it down, in fact it seemingly brought back her appetite.
Good luck hun x