How to check if 3 nodes in a row are identical C++?

I have a linkedList, I wanted to check if there are 3 nodes in a row that have the same data/value, if so i want to remove them from the list.

ex. 1, 2, 3, 4, 4, 4, 7, 5; // here from index 3-5 have same value, then the new list will be new list: 1, 2, 3, 7, 5

this is my code, I just got confused on how to keep track of the previous 2 values so I can campare them with the node that the current pointer pointing to.

//assume the rest of my code works fine

void Remove_ThreeDuplicates()
{
    Node *current= head;
    Node *prev = current;
    Node *prev_prev = prev;

    //keep track of identical found
    int i = 0;

    while(current->next != NULL)
   {
       prev_prev =head_ptr;
       prev = prev_prev->Next;
       current = prev->Next;


      //checks if nodes are identical
       if(prev_prev->data == prev->data && prev->data == current->data)
       {
         //remove the 3 identical nodes
         prev_prev = current->next;
         i++;
       }

   }

 cout<<i<<" three pairs of identical node found\n"l;

}