Sorry for the actual answers, I know GB usually is for silliness.
This is a common issue I hear it almost daily. The key thing is to not mess your kid up with punishment and negative reinforcement. That can result in a long life of bowel dysfunction that is not fun for anyone.
This website guidelines from Dr Knapp is a bit long and exhaustive but it is the most proven ideas for this age & issues.
http://www.rogerknapp.com/medical/pottytrainingrefusals.htmHere is the section on potty phobia:
Toilet avoidance or phobia
The child with toilet avoidance won't sit on the toilet. Usually, she refuses to do so without explanation. Occasionally she claims she is afraid to sit on the toilet. The main causes of toilet phobia are passing painful bowel movements, receiving a painful enema or suppository, or being punished while on the toilet. The child rarely fears the toilet itself but rather what might happen again in the bathroom. Children who have not had any painful past experiences on the toilet usually have a severe form of toilet training resistance in which they have taken an irrevocable stand about using the toilet. Until this barrier is overcome, toilet training cannot proceed.
The parent needs to reestablish a pleasant feeling in the child about the toilet or potty chair. Specific interventions for toilet phobias begin with using stool softeners to make bowel movements soft and pain free. Then the child can be reassured that bowel movements will "feel good" when they come out. The parent can desensitize the child to the toilet in the following six steps, giving a sweet or other small treat when the child passes each milestone:
child empties diaper contents into toiletchild passes a bowel movement into diaper while in bathroomchild passes a bowel movement into diaper while sitting on toilet with lid downchild does the same with lid upchild passes a bowel movement through a "magic diaper" (a diaper with a hole cut in it) into the toiletchild passes bowel movements into the toilet without the "magic diaper."For more about the "magic diaper" technique, see the discussion by Blum. The method also can be used for urine. Its success probably owes more to providing a face saving exit from a bad habit than desensitizing the child to a fear.
Good luck!
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