Why does it feel like there's cool water running down my arms? it doesn't hurt but i don't know if i should be concerned or not?

These paresthesias have varied causes. Sometimes is as simple as movements or pressure on the skin sending signals to the brain causing those sensations. More serious causes like neuropathy or multiple sclerosis have other neurological findings and symptoms like loss of sensation or numbness, loss of deep tendon reflexes, muscle weakness, other areas of body also being involved. See MD as needed