I think got pang tang like some kids r 'petty', but im not sure hw exactly it goes. My mum mentioned before when i was lil im very sensitive to pregnant women esp those in their early stages. If im carried by pregnant women i will have not b able to sleep peacefully that night. Needa wash with some leaves or something. Donno whats that call. So when im pregnant i stay away from lil children n no matter hw tempted i wont touch them at all, worry that will cause them bad sleep or whatever .
I think the best way is to keep yr child off from yr sis for the time being. Or mayb you can try bathing him with the leave water after meeting yr sis?