So you booked BA flights on BA.com but used your AA FF number for trip credit? If it's a BA (125) ticket and you are BA Gold then I don't see why the Gold line wouldn't help you. BA may eventually rebook your connection automatically, and also your first flight if it's eventually cancelled, but you would be wise to get in front of that ASAP.

There are a number of tools besides the airline websites to research alternate flights. matrix.itasoftware.com would be my go-to in this situation. You will get best results if you have specific alternate flights in hand when you call. BA flights will be easiest for them to switch you to, followed by OneWorld airlines like QR, and then other airlines outside the alliance.

Beyond that, I don't think anyone on this forum can be much help without knowing your final destination and whether your trip is on a single BA ticket.