Size medium Reformation dress (maybe xs)see description

reposhing this dress The dress came looking yellowish with yellowing armpit stains and small brownish stains on the lap area that was not disclosed before I purchased it. It looks like maybe someone spilled a brownish drink. I tried to clean up the stains by soaking the dress and hanging dry. It seems now to be shrunk maybe by 2 sizes. I have it next to a reformation dress that's size small behind and next to the white one to show the difference. The dress is maybe a xs? now but the tag says Medium. I can get measurements if anyone is interested in having them. I took pics of the stains that are still visible on the dress