arm weakness and chest and back pain

I am 67 years old and presently taking care of my husband who is in a wheelchair and wonder if my pain is due to strain.  yesterday for the first time i was carrying something and i nearly dropped it because my right arm suddenly became very weak.  i transferred it to my left and found that my left arm was weak and then i got cramping pains across my upper back and upper chest.  it lasted only about 10 seconds.  This morning the same thing happened but it lasted about 30 seconds.  i felt a little light headed as well so i sat down.  This didn't happen right after lifting or straining but in the morning before i actually did much.  Any suggestions as to what this may be?