After ICU and ventilation

Hi all, i am new but felt i needed more answers and help. I was misdiagonosed on 13th June 2019 with pharangitis and was then rushed to icu with influenza a, pneumonia and bronchitis. I was in ICU on a ventilator for 10 days and ive been out of hospital for a week and a bit. My worries are and i hope someone can maybe relate and tell me its normal, i get pain in my chest which moves around and in my back and neck. Im generally weak and very shakey and now get terrible headache but in my back of my head. Doctor said all is good and i am going to feel like this for a while up to 6 weeks even. Why though i dont understand and feeling anxious about it