I know this is HN, but you haven't really mentioned anything about novelty outside software. Now, I will try to not make assumptions, but is it perhaps that you are only seeking novelty in a very constrained way, which makes you feel uneasy about your choices?
What type of food do you eat? What hobbies do you pursue? Maybe you have a very monotonous life (or at least you think you have it) and try to compensate in your career with novelty.
If I were in your position, I would first write down when and where I experience these 'novelty rushes'. The key here is not looking at these notes after you write them for at least a couple of weeks. After a couple of weeks doing this, look at what you wrote and see if it maybe has to do with other factors in your life (maybe you rush to try something new after an argument with your wife, when you don't drink your coffee in the morning or when you don't go running for 1 or 2 days)
Perhaps it has nothing to do with your life outside this area, but maybe you just like reading documentation. At any rate, writing down what you are doing when you get these 'novelty rushes' would help you identify the problem. Hopefully.