I'm talking about moments when you watch a film and you bristle, or when you listen to music, etc.
What kind of neurotransmitter flow changes?
One thing is that we can't control the Goosebumps. It is an involuntary function caused by the Sympathetic Nervous System which is the major part of the Automatic Nervous System. The major function of the SNS is fight to flight response along with maintaining homeostasis in which case it internally will be alert maintaining body status from the background.
Before sending any response to target tissue when there is input to SNS it has to secrete neurotransmitters but before this to the sympatho-adrenal response of the body, as the preganglionic sympathetic fibers that end in the adrenal medulla (but also all other sympathetic fibers) secrete acetylcholine, which activates the great secretion of adrenaline (epinephrine) and to a lesser extent noradrenaline (norepinephrine) from it.
So whenever SNS senses (message flow is bidirectional) any stress it responds it in following action mentioned:
Once the receptors receive the information then the response flows to the target tissue via neurons with the help of the neurotransmitters. To explain goosebumps technically:
Goosebumps also occur when we listen to surprise songs, sad songs or some other kind of thrilling music. Researchers have tried to explain it and they call it "Frisson". Check out this small video which talks about it. It is nice:
Also refer to this website: Goosebumps