Right now I have a bit of a chest infection!
I can't really sleep because when I lie down I start coughing really badly, and it hurts. Do any of you have any advice on sleeping positions that are good for coughing, or any tips to help me get through the night?!

Get some medicine before worrying about sleeping position.
As for the position itself, get a pillow that puts your head not too high and not too low, it will ease your breathing :).

I've got some antibiotics to eventually cure the infection itself, but normal painkillers don't help with stopping the coughing that keeps me awake. It's so frustrating!
After experimenting with thick and thin pillows I eventually decided sleeping on my back or sides was a bad idea. I tried sleeping on my front and I coughed a lot less than before, but it looks like I have to wait for exhaustion to kick in before I get any decent rest.

Not fair!

Sleeping sitting up helps. You might cough more, but less stuff should settle in your lungs. Also prednisone, not sure if I spelled it right, would help. I have some on hand since I'm an asthmatic and had some for a mild case of pneumonia.

But I would go see a doctor first

I've heard it's helpful to use extra pillows when you sleep, so your head is raised up a bit, if that helps any.

Thank you for the replies!
i ended up losing a lot of sleep despite extra pillows and painkillers, but the antibiotics are really kicking in now.
I should be absolutely fine by next week!