That'd be pretty much a waste of Ket. You'd want a clean nasal passage in order to get the most of your ket.
If you're sick you should probably lay low on the druggin' until you're feeling better. Your health is more important than getting high, and not to mention the fact that doing more drugs will probably not help your sickness.
If you're turning to drugs to solve your problems and take the weight off your shoulders, you really need to look into getting clean(er). You're only 17(?), you have an entire life ahead of you, and you shouldnt be held back so young by a rising addiction.
If it's crystal or powder, the safest way to dose it (if its less than 300mg IMO) is to insufflate it. You could plug it or take it orally, but since the BA is so low you'd need a much higher dose to get to the same level as insufflating it.
If you're nose is still stuffy it means you're still sick. Wait until your healthy again, your body will thank you!