Thought loops and illusions. Same logic?

Hi , I am a software engineer and my daily works involves writing codes , but some months ago I noticed a strange behaviour in me that I am getting stuck if try to recall any program , when I actually see that I doubt myself like how in the first place I was able to write that ? If the same situation comes again will I be able to write the same logic ? And my mind goes in continuous thought loops again and again like how I did that ,I start thinking about that and end then my mind again starts thinking about that in the hope that I might get a proper resolution that satisfies me , how in future I will solve the same kind of problem , I have started doubting myself if I will be able to do my job in a proper way in future , because of this problem if I try to learn something new , again I find myself in the loop of illusions and thoughts . Sometimes I get illusions of the things that I know as I had learned those in past and applied , please help me as my mind is getting messed up .