5 week sleep challenges

Moms - anyone have any tips for getting baby to fall asleep without being held? I was told to keep the baby upright for at least 15 minutes to help with gas and prevent spit up. Because i do this, my baby often falls asleep in my arms after feeding. Now i’m concerned he won’t sleep if i’m not holding him or rocking him. He has been incredibly gassy and struggles to stay asleep sometimes because of it and with bowel movements so trying to relieve it as much as possible.