Double check that the image paths are correct for the artwork.
the ing tags:
<img src="artworks/<?php echo($row_WADAartworks['img']); ?>" alt="alt" class="img-responsive" style="width:100%; max-width:800px;">
may not be pointing to the correct location. double check the page source. to see if the path is correct in the source.
also, you have 4 repeat regions around the content, where you really only need 2.
one to repeat the WADAartworks recordset, and the other to repeat the ArtistName nested recordset