I think it might be Lactic acids
Stool (poo) is the chemical substance produced by the body that is associated with the pain of inflammation, as inflammation is pain in your backside.
What chemical causes what!
Inflammation causes pain on movement.
I think any pain in ”any hand” causes pain in both hands.
Capsaicin causes "spiciness"! See the related link to the Wiki page on it!
it causes pain reactions
mostly during the menstruation cycle causes the most pain
According to the link, below, the major chemical in a honey bee sting is "melittin".
Chemical weathering is caused by chemical reactions in the substance, for example, when oxidation causes rusting.
Arthritis causes pain, stiffness and swelling of joints.
There could be mulitple causes of ankle pain including but not limited to arthritis, tendonitis or a sprain.
There are several causes of spinal pain. The most common cause of spinal pain is disk degeneration. Another cause could be a herniated disk. Arthritis and poor posture are two other causes of spinal pain.