I was lucky and had a save where i did not take the potions into my inventory. So i just drank a potion to remove all stench, i think it was the grey one to the left..and then the yellow one, it said it smells like chicken..but don't take them from the table, just click and use them. Then i went to the spider and it was peaceful. A dialog box popped up and i chose "tickle left side between second and third leg", then it followed me to the hut of the questgiver.
