WAY OT -- Any Exterminators out there?

This is so way off topic but my husband and I are pulling our hair out. For the last month or so we have been over run with flies. We have cleaned out cabinets, poured bug killer down all the drains, got rid of the trash compactor, moved appliances, and searched high and low and can't find the source. We are getting exercise just by swatting! They are mostly in the kitchen and master bathroom. We think we finally have them gone and then walk back into one of the rooms and find at least a dozen flies. We have searched the internet for answers and it just tells us to find the source but we have tried to and can find none. My house is now the cleanest it has ever been and STILL there are flies. ANY ideas are welcome. HELP!

How awful!  That would drive me nuts.  My brother in law is starting a job as an exterminator in a couple of weeks but I know that doesn't help you now.  Hope you got it figured out.