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Sorry to hear that your dad isn't well.
My opinion is with the short notice, 3% up front and 0% for 12 isn't a bad offer. Credit cards don't always show up quickly in the mail and even ones that offer instant credit card numbers like AMEX don't always do so.
The Discover has plenty of credit available unless you made a typo, I would just use that card and transfer it to PenFed.