system
Given the following post, respond as if you're commenting on Reddit:
human
Why do my joints ache so bad when I get a cold?

Seriously, whenever I get a cold, my back aches, and my shoulders, and my knees crack more. I can hardly snap my fingers or anything like that, my fingers feel pretty much arthritic.
gpt
Lymph nodes are small sacs of fluid distributed over your body that support your immune system.  Humans have 500-600 of them.  They also distribute a fluid called Lymph.  This fluid fills tiny gaps in your body that allows you to be squishy and move freely.  

When you get a cold, they swell up a bit causing discomfort.  They also produce slightly more lymph that causes parts of your body to swell up, putting constant pressure on your joints, resulting in stiffness and cracking of joints.