Talk to Gynecologist on Muscles Pain Stress

I want yo ask about my muscular problems. Im facing shoulders upwards pain n some times back pain after my first baby's birth. It should be lack of sleep or iron?? Because i didn't use any supplements or multi vitamins after my delivery. I feel exhausted sometimes. My muscles get very tired ,when i did my daily routine domestic works like washing clothes, cooking etc and look after my baby day n night constantly without any break. Please suggest me some multi vitamins to boost my energy level that keep me fresh k active as well. Thanks