So my 3 month old twin son is not lifting his head and we are getting worried. My twin girl is doing…

So my 3 month old twin son is not lifting his head and we are getting worried. My twin girl is doing it great. He has a problem with his trachea, it's called Tracheomalachia or Lovyngotrachomalachia. Going to an ENT about it next week. Reason we know he has this is because he is a loud breather. The doctor said it most always fixes itself by 2 years old. So I don't know if him having this is affecting him lifting his head or not. Has anyone else had a baby that would just not lift their head and what did you have to do about it?