Thanks for writing to health care magic.
Green color of the stool only indicates that bowels are emptied early. Rapid bowel moment results in green colored stool. So one need not worry about that.
Burping helps in relieving abdominal pain
Frequent use of medicines should always be avoided in 5 week baby or for that matter any body.
Hope your baby is breastfed. Breast fed babies have less chance of infections and breast feeding helps in brain growth.
Hope this helps.