Doubly linked list, add node in-order

I want to keep my doubly linked list sorted all the time and keep the head and the tail node pointers updated. I managed to keep the head pointer updated in all operations but I can not keep track of the tail pointer. It only shows the last element as tail->info but can not go back as doing tail=tail->prev; here is my code:

AddInOrder(node* &head, node* &tail, int number) {     

    node *ptr=head; 

    if (head==NULL || number<head->info) {       

        node*temp=new node;

        temp->info=number; 
        temp->next=head;   
        temp->prev=NULL;
        head=temp;   
        tail=temp;    
        return 0;
    }

    while(ptr->next!=NULL && ptr->next->info<number) {         
        ptr=ptr->next;                                        
    }

    node*temp=new node;              
    temp->info=number;
    temp->next=ptr->next;
    temp->prev=ptr;
    ptr->next=temp;

    while(ptr->next!=NULL) {
        ptr=ptr->next;                 
    }

    tail=ptr;             

    return 0;
}