Yesterday my (also non Japanese) friend had a headache and we had to buy medicine in Japanese.
So I looked up how to say "headache" and add it to my vocabulary.
I found the word 頭痛{ずつう} and I suppose it could be used in sentences like 頭痛がある
But when I told my friend about 頭痛 he said "no that's not right." He said it's 頭{あたま}が痛{いた}い so you would make a sentence like 頭が痛いだ.
Obviously they both use the same characters but in different ways. Is the second sentence more colloquial? Is 頭痛 more technical? Are they both just as common?