Schedule anxiety

Hello everyone! I have a little boy who will be 4 months on the 29th. My husband and I had tried for years to get pregnant and had two miscarriages before conceiving and giving birth to Carter. My husband has a 9 year old of whom we have custody. I love my boys much, however I have struggled with PPD since Carter has been born. I stay at home with Carter but we are really busy with my 9 year old's hockey. We travel constantly and are always on the go. The last month has been going very well he was sleeping 7-9 hours and we were in a grove. However last week he was diagnosed with RSV. Since then his sleep has been a mess. I understand it's probably because he is sick. However this has really peaked my anxiety about sleep training. A daily schedule does not fit well into our live style. Everything I read states that in order to have good night sleep you have to have a daily schedule. I am beyond anxious at this point. Had anyone had success with good night sleep with out a daily schedule?