We can hope it's just due to deconditioning. Starting a new exercise program is always difficult. It takes time to get back in shape so take it slow and easy. If you continue to have the arm pain and chest pain, stop and call your doctor. Between the high cholesterol, weight and sedentary lifestyle it would probably be best to be checked first, make sure all systems are go so to speak.
I am 40, had a complete hysterectomy when I was 22 years old. High cholesterol about 265. High blood pressure, but with meds its stays in the prehypertension range. Overweight and mostly a sedentary lifestyle.
Sounds troublesome. Have you had a stress test or echo done recently? You don't mention your age either. This would be a good thing to mention to your doctor, sooner rather than later.