Bore da, just a quick question, how would I say the word “aching”?
I went for a walk but my legs are aching.
I played golf yesterday now my back is aching.
I was lifting a heavy parcel now my arms are aching.
I’m learning North but Southern would be of interest too,
Diolch
There are several ways to express this. The first that came to mind was
Mae fy mreichiau yn brifo. - My arms are aching/hurting
You could also say
Mae poen yn fy mreichiau. (lit. There is pain in my arms.)
I think these would be understood all throughout Wales, but I’d be happy to see someone weigh in with more northern knowledge. (There is also cur and dolur for pain, which have a northen ring to my ears, but other than dolur rhydd for diarrhea and cur pen for headache I have no idea how to use these)
“Brifo” is definitely used in the north, based on a Welsh course I did some years ago where the little girl was complaining after having to write out lines because she’d been naughty in school. If I remember correctly she said, “Mae fy mys i’n brifo. Mae fy mraich i’n brifo!” (My finger hurts. My arm hurts.)
For “cur pen”, you could say, “Mae gen i gur pen” (I have a head ache) or “Roedd gen i gur pen” (I had a headache) and the same for “dolur rhydd”.
Diolch for your help Hendrik, I like how to dolur rhydd 
Diolch for your help Margaret, really appreciate it
Diolch for your help Margaret, really appreciate it