Thank you for all your kind words and considerate advice.
My mum managed to find a suitable vet who wasn't TOO far away, she took him today.
So basically they had to wipe a lot of blood away to see what was going on, and it turns out his opening of the vent was BIG. It was at least 4x the size it should have been. They looked underneath his chest feathers and found it looked bruised.
In conclusion they decided it was PROBABLY a case of trauma, whether that was before we bought him or after, we do not know. However, they did mention that his wings were cut very short (by the breeder) and this could have been why he got injured - by falling to the bottom of the cage and not being able to fly.
Anyway, my mum says it was very difficult and they had 2 vets in there by the end trying to figure out if there was anything they could do. Vet said she COULD try doing a type of plastic surgery on the vent, but there really wasn't much skin left at all by then, so she said she really didn't think that would work.
In the end they all decided the best thing to do was to put him down, he'd lost lots and lots of blood, and his vent was in a right state.
She did also test for parasites just in case, but it came back negative.
So obviously I was (am) really upset when I came home from school to be told he had to be put down.
However, I now have a very good and reliable vet whom I can trust now. Also she amazingly only charged £30 for everything (fecale test, putting to sleep, and consultation). My mum says they were all in tears as he was such a sweet little thing but nothing could be done.
Anyhow, Prince (his male partner) is acting a little angry after losing his buddy. My un-tame Thisby has been talking to him though, and I hope they will get on well together once introduced.
However, I am worried now that Prince will become untame again once mixed with Thisby. What are your thoughts?
Oh Amy, I am so sorry your little budgie had to be put down, now he is free from pain and it is the hardest decision to have to make but it was made out of love and care for your budgie. I am glad you have found a great avian vet for the future. Fly high and free little one.
I saw your other thread and I am at a loss for words... I'm so sorry you had to go through this.
The breeder should have never sold you the severely injured little fellow. To me it seems he was pecked down there by some other bird... At least the poor boy is no longer suffering. You have my deepest sympathies.
Rest in peace, little one.
RIP sweet Tito (Summer 2008 - January 17th 2013).
You are missed and never will be forgotten.