DD is 5mo and she has a cold that didn't seem that bad until today. She has been coughing a lot today to the point that it makes her upset. She is happy and playful when she isn't coughing so that makes me feel better. But I would like to do something to help her clear her chest out.
A couple of days ago she started to put her fingers in her mouth and this made her throw up... should I let her continue doing this? I think it might help her clear her chest out enough to reduce all the coughing.
I also thought of bouncing her around as I carry her in a vertical position (don't laugh)... wouldn't this help gravitate the mucous down and away from her chest.
I don'know, so please help.

A warm bath with a bit of the vapor bath. Also you can try rubbing vapor rub. I believe J&J makes one safe for 4 mo on and I got one at the health food store safe for all ages by Baby Spa

You can put a couple drops of tea tree oil and Eucylptus oil (sp :confused: ) in a humidifier for her. Also put a drop or two of each in some olive oil and rub it on her chest and back. Try to let her sleep as much as possible, help keep her head a bit elevated w/pillows or laying her upper half on your body. You can also take extra vit. C and Bee Propylis etc. that she'll get in your milk. Hope she feels better soon. :)

I don't see how throwing up will help clear her lungs. Those are 2 separate body systems.
When mine got congested, I'd sit in the bathroom with the shower running only hot water to steam up the air. The humidity loosens the congestion so the child's coughing can more easily bring it up out of the lungs and bronchial tubes.
The alternative, and what worked better for our kids, is to take them outside into the cool air (this works better in Fall, Spring, or Winter obviously) because cold air also loosens congestion--makes it more liquid and thus easier to bring up and out.
Different kids respond better to one or the other.
I also elevated the head of the child's sleep surface, sidecarred crib in DD's case.