From your description, it sounds like the plastic wrap is either in your pharynx or esophagus and that it truly is small with a surface area less than a dime. Assuming that you have an anatomically and functionally normal esophagus, and had no problem swallowing anything before this incident, you should not need to vomit or go to the emergency room (ER). The other assumption is that the plastic wrap is soft, with no hard edges that could lodge in the esophageal wall.
Ideally, one would want to allow this material enough time to pass into your stomach. Facilitating this is, in part, dependent on carrying it into the stomach with food or liquid. What often works is the repeat swallowing of boluses of bread without the crust or cereals such as thick Cream of Wheat. For liquids, the more viscous, semi-liquid, the better as it is more capable of carrying the plastic along than thin liquids. Examples of this would be milkshakes or yogurt.
However, if this material has not passed in 24 to 48 hours, you should seek medical advice, probably best from a gastroenterologist. If in the meantime your symptoms worsen – that is, with more difficulty swallowing or breathing, you should immediately be taken to the nearest ER.
Good luck.
also, when it seems to go down it comes back up. I think that it is because it weighs nothing and it can float