We went through this last week with out 7 week old DD. she usually sleeps and feeds really well but last week it all went to hell for about 4 days and then she just reverted to normal. We put it down to a growth spurt too.
Congratulations! Just wanted to add that all the health pro's I've ever talked to say that wet nappies on their own don't mean much but if she's having pooey ones that look normal that's a sign she's alright. Don't feel daft about nipping her round to your GP (again and again!) if you are worried though.
It sounds a little bit as though she may be going through an early growth spurt. They can last up to a week I'm afraid and, bizarrely, don't necessarily mean they eat more at the time. Small child here tended to take in more either just before, or just after a spurt, but never during.
I know the volumes of vomit can seem huge, but she will have managed to keep some of it in. Can you try feeding less, but more frequently (that worked for us)? Also, if no temperature, and nappies continue wet, then keeping an eye may be the best thing to do.
I'm not an expert though, it's just your experience sounds similar to mine with small child at that age so hope it helps you.
Hoping someone could reassure me if they have been through sonething similar?? My little girl is 7 weeks old and for the past 2 days has been really sleep (which she usually isnt) and not really taking her feeds. She usually takes anywhere between 3-5oz every 3-4hrs and now i am struggling to get 3/4oz down her. This morning she did take 5oz and vomitted wat seemed like the whole thing bk (she had 2 outfit changes) then shes gone back to havin very little and still bringing some back up. Tried giving her cool boiled water which she spits out. Also shes really struggling to bring up any wind (shes on infacol aswell). She literally wakes up for her feed crying. Has small amounts, is sick, screams for about 10 mins then falls back asleep.
Have spoke to the GP n he said aslong as shes got plenty of wet nappies jus keep an eye on her.