Stuffy nose 5wks and still going?

My 5wk old is stuffy and has been since just about birth, have gone through formula change, laundry det change, water change you name it we've changed it, first Dr trip was alittle green inside, nothing done, second alittle more green was put on antibiotic, third more green another round of antibiotic finished that and still stuffy, sounds to be more like its on top of his palet (sp?) not in his nose or in the back of his throat. When hes up and around during the day seems better but at night omg he's terrible and yes the head of bed is up, humidifier on, air purifier running the whole nine yards, use saline spray and a very slow nipple for hard sucking just to help with some of the pull down, Im just about at witts end here does anyone please have any experience and any suggestion my mom died 3 years ago so I have absolutly no-one to run and cry to thank you so much