"Oes, mae braich dost gyda fi."

Translation: Yes, I have a sore arm.

[NicDafis]

Suggested "Yes, I've got a sore arm" as an alternative. Won't be doing this for every possessive, as I'm trying to Test Out quickly.

[tachwedd]

Surely 'I have a pain in my arm' is also acceptable?

[ErnieSmallholder]

Yes, I have an arm ache - was marked as wrong.