Your mind accusing you

How do I deal with my mind accusing me of something I’m not doing? For example, if you are walking, and your mind tells you that you are killing insects or bacteria, how do you deal with it? Or For example, if your skin gets itchy and you want to scratch but your mind tells you that you are killing ants or bacteria that might be causing your skin to be itchy. Your original intention was to scratch your skin because it’s itchy but your mind tells you that you are going to kill insects or bacteria that might be on your skin, you don’t listen to your mind and scratch your skin anyway. Is this bad karma? Sorry if this is hard to understand. I try to make it clear.