WHAT CAN I DO FOR HIM?!

My son is just over a month old and has been battling a cold for awhile now... I have tried the saline drops and then sucking his nose out with the bulb, doesn't work. I have tried the nosefrida and it does get the snot out of his nose but doesn't clear his congestion. I have also tried squirting the saline drops from the bulb into his nose and letting it come out of his other nostril but again, it's only temporary and then he's back to being stuffed up/congested again, to the point of it being hard for him to feed because it's hard for him to breathe, and he has been extremely sleepy from it. So my question is what else can I do for him to actually relieve the congestion where he is so little and I cant give him much? His doctor says it's just a cold and to let it run its course but its killing me seeing him having a hard time with it so I'd like to be able to do something to help him😭