Thank you for your query.
Breast feeding is an exhaustive process for the baby.
Babies usually perspire after a long session of breastfeeding
I hope there is no reason to worry.
You haven't mentioned the birth weight
of the baby...so it is difficult to comment on her growth.
If your baby sweats profusely and leaves the nipple during feeding and has heavy breathing ask your doctor to recommend an echocardiograph of the baby.
If you have any further queries you are free to consult me.Hope this answers your query.Wishing your child a speedy recovery.Have a nice day.