Girlfriend has swelling under eyes, getting larger and larger, no problems breathing, no nausea, no stomach issues. Itching and swelling under eyes, on the cheeks, and some on forehead. She eats seafood all her live (40 years old), but we suspect two possibilities: (1) canned crab from crab cakes last night, about 22 hours ago, (2) she tried some make-up at Sephora, but that was two days ago so much less likely.

The swelling is increasing from morning to evening. Its now October 13, 2013, 8:27 PM in San Francisco.

Question: do we wait it out, or should we go to emergency room?

You should definitely take her to emerg. Why even wait here while you get answers?