It is normal to have the bad taste in mouth and whitish slough in the extraction socket after 3 days of extraction. Basically it is due to food lodgement. Try to keep the area clean. Do warm saline rinses 3-4 times a day. If there is no acute pain or swelling then there is nothing to worry but oral hygiene has to be maintained as the chances of secondary infection are always there which can lead to dry socket formation which a very painful condition. For more info on dos and dont's after tooth extraction you can read this article... http://www.identalhub.com/article_do's-and-don'ts-after-tooth-extraction-153.aspx