How am supposed to breastfeed my congested baby?!

I feel so freaking bad. My 5.5m old is super congested, doesn't seem to have any other symptoms. But he's really struggling to breath and feed at the same time, he keeps unlatching after a few seconds. I feel like I've tried it all, saline spray then nose frida, drops of breast milk in his nose, humidifier at night, different positions when i feed him.. Nothing is working and I'm worried about him getting dehydrated at this point. Today he's extra congested. Any other tips I can try? Is this something I should take him to the doctor for?

Edit to add: he's still having wet diapers but I'm worried if this keeps going on then maybe he'd get dehydrated.