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I would suggest that you immediately give her a dose of benadryl. My vet recommends a dose of 12.5 mg for a dog under 20 lbs and 25 mg for one that is larger than that.
It sounds like he's having an allergic reaction to something. Keep an eye out for labored breathing, increased respirations and disorientation. If you see any of these, you will need to see your vet.
You will need to see your vet tomorrow to find out what the cause is and to discuss your treatment options.
Let me know if you still have questions.