Like already said way too young to be of breast milk.
It's vital for a bunny to stay at least 8 weeks on breast milk, ideally 10 weeks.
Bunnies are very good at hiding any symptoms, as their survival in the wild depends on it.
Jet will now need a lot of love from you, but without hassling him.
Let him come to you. Talk to him gently.
Stroke him while he is on the ground, give him nose rubs while his feet are firmly on the ground.
He needs to feel loved and secure as bunnies do not cope well at all with stress.
Do not pick him up! (unless absolutely necessary to examine him).
To be picked up means for a bunny that it has been caught by a Bird of Prey, Fox etc. and that he is about to be killed. Hence being picked up causes a tremendous amount of stress to a bunny.
Also pls explain to your girls that they cannot pick the bunny up, but show them how to stroke the bunny on the ground.
Generally bunnies find it relaxing if you gently and very slowly stroke them along the back starting from the head (hope that makes sense)
If a bunny enjoys being stroked by you, it will gently grind it's teeth (we call it bunny purrs)
Once he purrs while you are stroking him, you know you are doing it right.
You need to watch him very closely for any change in behaviour.
Often a sick bunny will show no symptoms until it's too late, however you will see tiny changes in behaviour.
Like already said you need him checked by a bunny savvy vet as a matter of urgency (unfortunately there are only very few bunny savvy vets).
His poo needs to be sent off to a laboratory to make the correct diagnosis and prescribe the correct meds.
I am not a vet and my recommendations regarding feeding him are just based on my own experiences with rabbits.
If anybody else here could pls correct me if my recommendations are not correct
You also need to be careful with what you feed him, no sudden change in diet, no bunny ready mixed food (I would also only give very few pellets as they contain too much starch which causes yeast infection, which can cause bloat).
Do not ever give him Cow's Milk. No sweets ever!
No fresh greens (until you have been given the go ahead by a vet), no fruits at this age.
I would only feed very high quality hay and maybe some very highly diluted camomile and fennel tea (but he will need other supplements from the vets such as Bio Lapis and probably some multi vits, apart from the proper meds he will need after being properly diagnosed).
Once he has got the all clear from the vets and is stable you can slowly introduce other vegetables.
keep him out of the heat as bunnies do not tolerate heat well.
I would also always have Infacol for small babies ready (about £2.99 from any big supermarket). Bloat kills bunnies within hours, as bunnies cannot get rid of bloat.
Watch him super carefully, if he stops eating it's an emergency!
Ok, this may all sound super complicated, but once you know your bunny you will be able to interpret his behaviour.
Bunnies are amazing animals and being a bunny owner is very rewarding. they are super intelligent and will never stop to amaze you.
My 8,5 year old bunny was a super sick 5wk old baby when I got him and the first 4 wks were touch and go. Every morning during this time I expected to wake up to a dead bunny baby.
He pulled through and it was so worth the effort.
I have always been a cat and dog lover, but I would now never have any other animal than a bunny.