Are Dizziness And Mild Shortness Of Breath While Having Diabetes A Cause For Concern?

I am 66...have been diabetic for 25 years but well under control. Normally feel great..... still working.... walk a lot... have lost about 65 pounds over last 18 months and feeling good until a few days ago. Sugar readings are fine but the second reading on my BP is a little low..ave 118/55 but pulse rate used to be in 70 s resting... now has been running 41-48. Some dizziness and mild shortness of breath. Have not been sick... dad died of congestive heart failure at 79...he was a smoker....I am a non smoker and non drinker.....