I've listened carefully and I'm sure she is saying *pen dost. I know it shouldn't be but that's what it sounds like. Anyone agree?
A previous comment said tost was unusual in the North. Dolurus and poenus are possible alternatives?
Depending on where 'the North' is, you may come across cur pen for 'a headache'.
(There are five or six main dialect areas in Wales, not two.)
Most courses and books use either N or S Welsh.
Although there are variants within these areas.
Don't know about you but at the moment it's prepositions are giving me a "pen tost" and "mae esgyrn tost gyda fi" anyway!