No need to panic. They probably wont take it any farther. They are just working their way up the food chain shutting down the sellers as they go. They are mainly searching for the person who is selling in large bulks and mostly for where this person is getting their large quantities from..
Send them the info they are requesting by email and be professional about it. Let them know how you obtained the goods and that you were under the impression that they were legitimate goods..Keep a copy of all correspondence with them.
Next time keep in mind that most all designer goods companies (parent companies) such as lets say nike, ralph lauren, lacoste, and all of those companies strictly sell their goods through boutiques, and major dept stores..They also have distributors who have 'master licences' to distribute to the dept stores and boutiques. They never wholesale their goods to anyone. The only way to get authentic designer goods is through liquidators, closeout and surplus dealers. These dealers buy the overstocks and end of season goods from the dept stores and boutiques at the end of the season and just before the new styles and seasons good come out.
In addition always ask for a 'sanitized invoice' when buying designer goods (branded goods). If they are authentic goods the dealer will have no problem in providing you with this invoice. If they start giving excuses about why they cannot provide this service then you should not buy from them and the goods are probably going to be fake....
When I sell designer goods or any branded goods, I normally send a copy of the invoice (a hard copy) to ebay or whatever site I'm selling through along with an 'intent to resell' notice, plus copies of the tags and labels..Of course if you are only selling 4 or 5 then you can probably forego this, but if you are going to be selling a brand on a regular basis then it's a good idea and can save you alot of headaches...
Too, if you do have authentic goods and purchased them from a legitimate dealer then you have the right to resell them and are protected under the 'first right of sale' law. Keeping in mind that even though you can legally resale these goods, you cannot use their photos, descriptions, or any other of their copyrighted materials....