I think I figured it out. It lookes like removing the space after "Contact_Label_Contact_Header " was the culprit? Not sure, but it worked when I pulled it out.
Also here is how I added all the rest of them. There is probably an easier way to accomplish this but I am just learning so this just made sense. If anyone would like to send a simpler solution I would be interested in knowing it.
<?php echo(str_replace("_"," ",str_replace("Contact_Label_Contact_Header", "",str_replace("General_Info_Label_General_Info_Header", "",str_replace("About_Label_About_Header", "",str_replace("More_Details_Label_More_Detail_Header", "",str_replace("Branding_Label_Branding_Header", "",str_replace("Media_Label_Media_Header", "",str_replace("Practice_Goals_Labe_Practice_Goals", "",str_replace("HiddenFields_fields", "", $pkey)))))))))); ?>:</th>