I sent a message to the doctor to prescribe medicine, but I haven't returned the message for several days.

The doctor is very busy and suggests going directly to the hospital.

Doctors are really busy sometimes. For example, surgeons sometimes have to perform some operations, and it is definitely not enough to reply to your message for a few hours. In fact, doctors can't return information, which has nothing to do with being busy or not. No matter how busy a doctor is, he always has time to look at his mobile phone and text messages. So if a person can't spare the time to reply to your message, maybe you don't have much weight in his mind, or he thinks you are an insignificant person, so you can reply or not.