Numbness in the left arm and lower left leg with pain under the left arm started around 4 hours ago, have had some pain in the upper stomach and back

Go to a doctor or ED. Based on the limited info, you may be experiencing a serious heart problem. You should not be sitting around surfing the net.
The . The onset of numbness on one side of the body could be a sign of a stroke and you need to call 911 right away. If you are suffering an ischemic stroke (due to a blood clot in the brain) your body may be compensating due to the loss of function on the left side, which can, in turn, cause feelings of pain in your body. Go to the emergency room.