When it was working did it use the parentheses that are showing in the image there? If not, I'd say that's a clue. If it just suddenly stopped working, something changed....was any code altered around the same time or anything else done?
It looks to me like the variable $num is not being filled or evaluated, and what's left are just the parentheses that surround it.
Try this....instead of this line:
echo '<option value="'.$row[0].'">'.$row[0].' ( '.$num.' )</option>';
...use this line and tell me if there's any difference:
print "<option value=\"$row[0]\">$row[0] ($num)</option>";
Finally, if you view the source of the dropdown in the page, does it show any values in the 'option value=' sections?