Trembling Bunny

My 4 year old English spot trembles when she is sitting or lying. It is not noticeable unless you actually watch closely. It is very minute. As soon as she stands or does something it goes. She is very active, eats and drinks and does her business all normally. She lives with a 4 year old female Dutch who seems normal. Both are spayed and spend at least 8 hours a day in an outdoor pen. At night she lives with the Dutch in a large hutch.

Is it trembling from breathing? I notice that sometimes after Bandit's been moving around, when he flops down sometimes his breathing and nose twitching causes his whole body to tremble a little.

It is not a breathing issue. Perhaps trembling may have been too strong a word. Its more like a constant quivering. Almost like a fine, very fine vibration. She is not exposed to strong sun and she is not cold. I noticed it a few days ago and I only see it when she is lying or standing and doing nothing. This morning so far, she is normal but I might see it again tonight when I put her back into her hutch. She is not frightened.
Her name is Bandita!

Is it maybe to do with the tooth purring or chattering a bun will do when content? That can sometimes cause their body to vibrate a bit.

I would like to think its that but can't say. She is a domestic rabbit whom I rescued from the wild and is not the kind who would sit in my lap or accept petting. She is well taken care of. The quivering/trembling is not always there and as I wrote she is very active. Its not a case of overheating or too being too cold.

Along with the trembling, this week she suffered a lost nail! She was shaking quite a bit at the vet but I figured it was nerves and pain. She has survived the nail episode but is still quivering/trembling but not too obvious. She eats, drinks and does all she should be doing but I find she is not as active as she was. Maybe today she is still feeling the nail pain.

At the suggestion of the moderator I have moved this post here. was not aware the post I was replying to was 8 years old. This is the latest.
I am upset and confused. When the vet checked her heart she said she could not her it from her back and had to reach under to her chest. Said it could be a lung problem. Heartbeat was 240 and body tem was 101.9. She strongly suggested chest x-rays ($215.00) as she thought asthma. I agreed and she later said it is from her perspective asthma but would like a specialist to look at ($70). The radiologist confirmed asthma and stated she was obese and had a mass by her heart which in her opinion was not dangerous. The bunny weighs 2.5kg and has forever. All of them weigh the same and they all get 1/4 cup of pellets as food plus hay and vegetables.
Now the vet wants me to put her on an inhaler ($75) plus the medicine which will come from my local pharmacy. And a course of Baytril.
Last week for an unrelated item I took her to a local vet and while there he checked her vitals and had no trouble hearing her heart. And she shows no signs of asthma such as wheezing, sniffles or noise in her chest. I mentioned this to the vet and she said rabbits are like that. They show nothing and then they die.
I have spoken to a few knowledgeable rabbit folk and they think what she is proposing is a bit much.
Bandita acts normal in every respect and occasionally she goes into a rapid breathing spell which lasts no more than 15 seconds. I have been watching her and if anything she seems no worse.
I can afford the treatment but do not want to put her in a mask as an inhaler. So my predicament is do I subject her to the medication or wait and see for a bit?