Just got my lower right wisdom tooth out 4 days ago. it looks like a stitch fell out an now a whole with white stuff in it. is this normal?

Socket?: May just be some slough which is some inflammatory tissue that forms over the empty tooth socket during the healing process. Does however need examination by dentist or doctor to be sure and urgently if increasing pain or swelling to exclude infection.

Post Op: What you describe sounds within the range of normal and I wouldn't worry about it unless you have pain or swelling. Having said that, you should always discuss this with the dentist who extracted the tooth and be seen for a follow up visit to check on healing.

Sounds normal: Especially if you have reservable stitches. As long as pain from the surgery is diminishing daily, and you don't have foul taste or smell, what you are experiencing is normal. If you have even the slightest question, however, you should contact the dentist or specialist Oral Surgeon who did your extraction for a post-surgical evaluation.