Hello You are smoking from a long period ( as duration you didn t mention in your query but it was very important for diagnostic purposes). Now having shortness of breath, numbness in the forearm left side with itching in numbness area. These symptoms may be due to these reasons, these includes. 1 Hypercholestrolaemia or Atherosclerosis , a process of progressive thickening and hardening of the walls of medium-sized & large arteries as a result of fat deposition ( cholesterol-lipid-calcium deposits) on their intimal walls. . Risks factors include age , male, sex, dyspilpidemia, hypertension , smoking diabetes and genetic .Diagnosis can be confirmed by arteriography ( angiography) and doppler test . As you mentioned that you are going to visit a cardiologist so please consult as early as possible. 2 Coronary artery disease , same as mentioned above reason. 3 Peripheral neuropathy may be the another reason of such symptoms ,so please get in M R I of this part . In my opinion consultation with a cardiologist will be helpful. Good luck.