My little one (now 3 months) had the same exact issue. She had extremely stinky gas (and loud too)and would only have a bowel movment about 1 time a week. My doctor said this was completely normal for breastfed babies. Some babies are just stinkier than others. Their little bodies digest the breastmilk so effienctly that sometimes they dont have a bowel movement everyday. We used Gripe water for her gas pain and that seemed to help. All I can say is as she has grown the smelly gas has subsided. Good luck!