Reactive Attachment Disorder

After the birth of my son which was last year, he always seemed annoyed and unhappy. When I consult the doctor regarding this, they told me it is due to Reactive Attachment Disorder. When I searched on the internet for some information regarding it, I got scared. I am attaching a website for reference Can anyone help me in explaining to me that is this disease is something that I should be worried about? Because I am very worried about my son."https://www.scientificanimations.com/3d-medical-animation-describing-reactive-attachment-disorder/"