Try calling web support (or reaching the web support desk somehow), tell them you want help validating your credit balance, and ask if they can help + give you the ticket numbers or record locators purchased with the credits.
I once needed help with credits I thought the balance was off and this is how I was transferred / it transpired.

Personally I would try to get the information first about what happened to these credits (e.g., what ticket numbers). If those aren't your ticket numbers, you can then pursue the question with AA security saying there are ticket numbers not in my name I didn't authorize (here they are) used with my credits.