
With the C.Sections we've had, our bitches were always given antibiotics, and in NO case, did I have to remove the puppies from her, or were they showing any signs of problems from the antibiotics coming through the milk. You could counter this possibility by giving the puppies a very tiny amount of natural yogurt (probiotic).
Do you have a mentor you can call on because, given I'm no vet but do have experience of bitches being given antibiotics, my inclination would be to get these puppies back on mum asap. What infection did mum get because I suppose removing the litter might be down to her infection, not the antibiotics.
I have never used Lactol, using Esbilac if I've needed bitch milk replacer. Or goats milk which won't have all that a bitch replacer milk should have in it. It is close in make up to bitch milk however. How often are you feeding the puppies - they need, at only 3 days old, to be fed every 2 hours, right around the clock. Which with 8, bottling, is bound to be an endless task, and tube feeding would be faster. And you will need to be doing the peeing and poohing she'd have been doing and which is vital, for the comfort of the puppies. Also if she's not with them, do you have them warm enough - 80F on the floor of the whelping box? Morbidly chilled puppies won't nurse and will die.
Her milk should come back, once you get the puppies nursing and provided she's eating up okay. This is far from an ideal situation, which you'll realise!!
I hope you can get this sorted out asap.
Add - I now realise this OP was a few days ago, so clearly you have them all back with her now - GOOD. For the smaller one, get her onto the teat, a middle one which she'll be more likel to manage, first so she gets a good go before the others push her off. And again natural yogurt, just a tiny amount, may help her digestive problems.