My mom Cat is licking kittens genital area in excess bay kitten is getting chapped and raw. 3 week old kitten is very uncomfortable when mom licks. What should I do

Is this her first kittens? Does the kitten use the litter box on its own? You could try putting some vaseline on the sore area, and keeping it away from the mama overnight that should get it to start healing. Or you could put some bitter apple (makes sure it is cat safe). If I did the bitter apple I would not let it get into contact with the raw area, just put it in the area surrounding it. Also it may be a good idea to offer the kittens some soften dry kitten food. It may be a good idea to get them less dependent on mama. Another thing is the kitten may have worms. Mama may sense that there is a problem and she may be showing concern because she can smell them. Maybe that is something you need to call the vet and ask about.