Hello there. My name isXXXXX and I am very sorry to hear about Maya. Giving her benadryl is a very good choice as it is quite possible that she got bit or stung by something and this is an allergic reaction. You have to give the benadryl a bit of time to work when given orally. it can take up to a couple hours. You can also give her some tylenol at a dose of 5 mg per pound every 12 hours. This reduces pain and inflammation also. You can repeat the benadryl dose is 2 hours initially then dose every 8 hours. Hopefully within a few hours you will see decrease inflammation. You can also apply a ice pack to the swollen area for 10 -15 minutes every 4 hours. All these combined will give good relief from the pain and swelling caused by an insect bite or sting. If the condition is still present in the morning have her seen by your vet to make sure that it is not something else going on like a tooth root abscess which often times causes swelling in the face that looks similar and can appear suddenly. Also if anything worsens such as swelling, pain, breathing difficulty, hives, etc then she should be seen tonight to receive additional medications to reverse this reaction. I hope this helps and I hope this makes sense. Please let me know if you have any additional questions or concerns. I would be happy to help. Please do not forget to rate my response so I receive credit for my time. Thank you!