is it a tumor?

Question
MY rabbit who is now is 5 yrs old, on her back hind leg the bump within 2 weeks kept growing. Its soft around the hind leg like theres puss possibly but I noticed a red round thing obviosly thought it would hopefully be a blood blister that I could take care of. within a day 3 weeks later from when I saw her leg blowing up and the red circle I was hoping was part of the infection is now hard and popping out more.She was unfortunately hurt when she was 3-4 months old and this is the leg i took her to the vet for when she was a baby. Please if you can tell me if it hopefully is a cyst or possibly a tumor. like I mentioned its soft around the hard whatever it is. little smaller than a marble. If u have a picture of tumor thatd help me out n do you think a tumor can grow that fast?

Answer
My first thought here is a warble.  That is the larvae of a large fuzzy fly.  The larvae will grom inside the host...see a lot of squirrels with this.  It will start out as a small bump and will noticably larger day by day.  It is usually found on the neck, sides and hind quarter.  The body will respond as it would any infection, you would see pus.  The center of the growth is usually red....and if you look carefully, you might see the larvae's gill come up for air.  It's really odd looking.  If it is a warble, is should be extraced by a skilled vet.  If the larvae's is compromised inside the host, it releases a toxin that is usually fatal.

This is a case that I fully suggest a vet's help.  Not being able to see this issue is really limiting my suggestions here.  But if it's growing that fast and looks like you describe, my bet is a warble.