If this number is unique per change, it's easy. If this number is global it can't be done without an external tool.
Enable a custom field of number type. Name it for example "rollback counter". Modify the change templates to set "rollback counter" to 0 on change creation, or create a db rule when a new change is created to set rollback counter to 0. This must be done otherwise the "Add" function will not work.
Enable a custom text field to hold the value of the previous status, name it for example "prev status".
Create a UI rule when item is opened to set prev status to Status.
Then create a db rule that does the following: When item is changed and previous status=Released to Production and Status(*)=Build and Test to update data and set rollback counter to add 1.0 to rollback counter.
(*) means that you must check "Evaluate this rule when this field has been changed".