HELP! BF baby puking every time I try formula

[babyblabber]

DD2 is 5 weeks and almost exclusively breastfed. From day one we have given her a bottle of formula almost every day as I'm self employed and need to be able to leave her for the odd day here and there, starting next Wednesday!!!

All was fine til about a week or so ago and now everytime she has formula she projectile vomits about 2-3 hours later. She usually only takes around 30mls of formula (she's not mad about it & it's really just to get her used to it, DD1 refused bottles completely til I gave up BF cold turkey at 4 months & it was very stressful) and she breastfeeds afterwards.

I've tried a different brand of formula today but she still puked. I hate pumping and wouldn't really have the time with 3 kids to mind & I intend on switching totally to formula by around 4 months so I need her to be able to take it.

Am gettin really stressed about leaving her next Wednesday. Anyone experience this or know what's going on?!!!

Ps I didn't give her a bottle two days this week and no puking so am sure that's the problem

My son used to puke projectile 2hrs after solids unless completely pureed, and turned out he was coeliac, i.e. gluten intolerant. He used to puke whatever the food was, so I did not realise that gluten was the problem for ages, but since learnt that the coeliac disease meant gut lining was inflamed so whatever he ate caused the puking. It may be an intolerance to something in the milk, lactose (sugar) or casein(protein)?