The abnormal sensation in your left arm is described as"paresthesia" which can be seen in many conditions. Such sensationsmay be due to abnormal nerve supply to the limb or due to reduced blood supply.
So, you will have to do some tests to detect or exclude some conditions like hypothyroidism
, diabetes, vasculitis like polyarteritis nodosa, TIA or mild stroke: these are some of the vascular causes. Spinal arthritis due to rheumatoid arthritis, ostoearthritis, psoriatic arthropathy , inflammatory arthritis are sometimes associated.
You should consult a neurologist or internal medicine specialist to identify whether your symptoms are dyue to neural or vascular causes. Accordingly the treatment will be determined.
You may do a color doppler ultrasound of the left arm to see wheteher there is arterial disorder.
I hope my answer is helpful to you. For accepting the answer, please press the "GREEN ACCEPT" button.
I would be highly obliged for a POSITIVE FEEDBACK and BONUS from you.