Cradle cap and bumps on her face and neck- may be due to seborrheic dermatitis- which is quite common in babies. You may apply baby shampoo every alternate day for the scalp
If the lesions in the face and neck are severe- mild steroid
creams can be applied after getting prescribed by a Pediatrician
In most of the babies- Seborrheic Dermatitis is self limiting and will go off on its own.
Regarding the fluid coming from behind the ear- do you see any small hole through which the liquid comes out? If so it might be a sinus. Though such sinuses
are seen before the ears only, rarely it can happen behind ears too.
Usually nothing is done much for such sinuses- unless it has some complications like repeated infections.
Hope my answer helps you.
Wish your Little one good health.