Even misdemeanor arrests are serious business.
Theft is theft. If you get convicted in theft once and later pick up another petty theft charge, that one could be a felony. It is very important to fight the first charge vigorously to avoid that consequence. Call a criminal defense attorney and discuss defense of this matter. Don't give up hope.
Always remember that you have rights: "Say nothing, and don't help them arrest you." You have the absolute right to remain silent. You can always say "No!" to a request to search. But your rights mean nothing if you don't know them and assert them. If you want this type of help contact a criminal defense attorney.