We have a growing water spot/mold spot in the ceiling on our 2nd floor. Water is leaking from somewhere and we assume it's from the roof, but don't know for sure.

We tried going up into the attic but couldn't see anything (Of course, I'm not sure what I was expecting to find)

I'm guessing I may also need to replace the ceiling drywall.

Is a roofer the best person to come explore the leak or is there another professional I should try?

Any suggestions?