A casual Kansai variant of 'どうしたの?', used to ask 'what's the matter?' or 'what's wrong?'.
顔色悪いけど、どうしたん？
You look pale — what's wrong?
泣いてるやん。どうしたん、話してごらん。
You're crying. What's wrong? Try telling me.
遅いなあ。電車止まってるん？ どうしたん？
You're late. Did the train stop? What's up?
なんか元気ないけど、どうしたんや？
You don't seem yourself — what's up?