I just read this and feel terrible for you. It is a horrible feelign and you just feel so violated.
I went through a lot of the same stuff when my wallet was stolen at school. Ugh. Not fun.
If it makes you feel any better, when a card is denied, we (cashiers) do not have anything that tells us why. Sometimes it just says Not Valid, or Denied, but most do not give it a second thought and just ask to try one more time, and then ask if they want to try with a different payment, or combined types of tender. We (at the store I've worked at for a few years) were taught to practice disrection, and to be nice, because you never know what could possible be going on. A lot of people even have had some sort of problem with paying with cards (debit, credit, whatever) because of bank errors, suspicious activity, or downtime/problems, say, in our automatic card readers (sometimes you have to ask the cashier to swipe the card themselves on the actual register).
Also, we do not keep numbers of credit cards, everything ends with the last four numbers, and not one person in the store has access to it. It goes automatically via computer to the bank, and we have a little slip that just proves the card was used (with date, time, store number, stuff like that pertaining to the store) that is taken to the bank (but no information is on there that could be used to steal card numbers or info). Hope that eases your mind a little bit. I know I was petrified to buy anything when I got my new accounts (my SSN and checking account had been used) and cards, and still have a hard time trusting people.
I hope everything get taken care of, and you can enjoy thanksgiving stress-free