Bump on Ear

Our rabbit has a bump on on of its ears similar to a zit. It has a small sore at the top on the bump. She has not be scratching at it and it isn't red unless we mess with it. It doesn't seem to cause her pain either. Should we monitor the bump and see if it goes away or take her to the vet?

I believe I am having a similar problem with my bunny. I posted a thread about it... I thought my bunnies bump turned into a Scab. By Any chance does it look like any of the pictures I attached below?
   
A few days ago I noticed a circular ring on Floppers ear.
   
The next day the circle grew into a black rough bump. The rough lump on her ear was bigger than the previous days ring.
   
Today the black rough bump looks like it turned into a Scab. Today I can see some pink.
   
I cannot figure out what this is or could have caused this?
   
Does your bunnies bump look like what is on my bunnies ear?
   
See pictures below.
   
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