If you are trying to get something like this https://ibb.co/KLKNjLt as a result, doing it via "high poly-low poly" method is a waist of time, usually I handpaint things like this, how to handpaint normal map is science on its own. Regarding your case I don't know what steps you take and what is your high poly-low poly workflow, obviously there is a mistake in the process. If whole of this that I wrote is not what you are trying to achive then you need to be more precise, helping someone on the forum is difficult enough even more with lack of exact details of the problem.