Ah good old N-ethyl-N-(o-methylphenyl) -2-butenamide. The name rolls off the tongue but the pure oil needs a wide label on the bottle! In a laboratory, the substance is sometimes labelled with its official IUPAC name,
N-ethyl-N-(2-methylphenyl)but-2-enamide.
The oil is insoluble in water but is soluble in the majority of alcohols. The pure product is usually colourless but can have a yellowish tinge due to impurities that are sometimes introduced during synthesis.
Crotamiton is an Aniilide, which are organic compounds made from other organic compounds called oxoacids. What happens in very simple terms is that part of the structure of certain oxoacids are removed an added to a very unpleasant chemical called aniline. Aniline itself has a huge number of industrial uses from rubber manufacture, dyes, paracetamol and weed killers to name but a few.
Crotamiton can indeed kill the scabies mite but it's not as effective as more modern treatments. Crotamiton cream application to scabies infestations can have a success rate of as low as 50%, which is not really that good. I do appreciate that you have found it amazingly good, but there's statistics for you!
As far as its mechanism of action is concerned as a scabicide or antipruritic, no one really knows. It is possible to follow certain key steps of the behaviour of the compound at a biochemical level via key insect metabolism pathways, but I'm afraid that we come to a dead end at one very important metabolic stage. Why it works as an antipruritic has never been explained in the scientific press properly and again, no one really knows.
As biochemist with some knowledge of toxicology, I know that crotamiton is structurally closely related to a number of compounds found in nature that are quite toxic and I've a fair idea of the mechanism of action based upon their structure. I'm afraid though that it's much too complex a theory to put forward here.