如何根据行标题替换单元格的内容？

I need to search every cell in row 1 (a1 to dv1) for the instance where "doc1" is followed in the subsequent cell in that row by "doc2." Then I need to concatenate the contents of what's in the cell one row below the cell containing "doc1" with what's in the cell one row below the cell containing "doc2", separated by a comma, and replacing the text in what's in the cell below the cell containing "doc1".I need to search every cell in row 1 (a1 to dv1