Imagine you are deep inside a very sophisticated math question and just when you are finding the solution your friend comes to you and brings up a very irrelevant matter! You want to show your disapproval and your displeasure. Does the self-made sentence bellow work here? If not, I was wondering if you could let me know an alternative for that:
Tom: - What the hell you're doin' Andy?
Andy: - What's wrong man?
Tom: - Nothing! You just brought up this matter very untimely.
I googled the word "untimely", but it seems there is something wrong with it while in my dictionary it is the best choice for such a situation. (This is a Farsi-English Dictionary.)