
Sorry Sam3 Missed that on your first post.
The milk mix may be a little to strong? try watering it very slightly. If it carries on a quick call to the vet seems like the best idea, they are very prone to infection without Mums milk so better safe than sorry. Did the vet give any antibiotics to give them a fighting chance when they were born?
Forgive me if I'm being a little inconsiderate but did Mum feed them at all or did you loose her before she could? The vet may give some ABX to help them over this danger time.
You could try a little solid food if they are well grown it's not to early with an orphaned little and may help a bit. Let us know how you go on.
Best of luck with your babies.