I had Breast cancer Her2 positive had surgery radiation FEC-D D then Trastuzumab for a year. I hav

General health and lifestyle
1

A long time ago stage 4 breast cancer.  Had sugery radiation  regular FEC-D 

Then Trastuzumab for a year.  I'm constantly fatigued low Vit D Low Vitamin B12  Low Potassium sick of being tired . Any ideas why I have these issues.

2

Is there anyone that could explain why my vitamin levels stay low. I eat right exercise and am tired of being tired all the time.