Is the discharge coming out of the ear canal?
Look closely to see if there is any bite marks, sting wounds or injury?
I am concerned about why the tip is giving off discharge. If there has been no injury then something must have bitten or stung him and that is causing the reaction. Is the Benadryl working yet? If not it may be better to go ahead and get him in tonight rather then take a chance.
If there is no vet or emergency vet open in the area then you will want to do supportive care until he can be seen. You can use warm compresses on the ear to help encourage draining. Make sure you clean it well and dry it in between the compresses.
You can use cool compresses on the jaw and face to help with swelling. You can continue with the Benadryl as well. Be sure to use only the plain Benadryl formula. Giving Benadryl with other combination of meds could be fatal, so be sure to read the box. Liquid Benadryl is too high in alcohol content to be safely used for animals. Please use capsule or pill form. Here is a link with dosage instructions: http://www.petplace.com/drug-library/diphenhydramine-benadryl/page1.aspx
Make sure you get him in as soon as a vet or emergency vet in your area is open.
The most likely cause is a bite or a sting of some type. While a allergic reaction could be the cause it is less likely due to the drainage. There is also the possibility and very likely that he may have scraped it at some point over the last few days and it has become infected thus causing the drainage and the swelling.