So was it just the two fish you added, or all if them? Was not sure. What are your parameters? Sounds like stress and/or ammonia/nitrate issues.
Moving forward, if the fish makes it...Both of those fish, but especially the sweetlips, need a lot more room than a 150. I'm sticking with my observations over the years that putting fish in "too small " tanks causes problems, regardless of how small they currently are. Sites that give recommended sizes usually give minimums, which to me, relates to a minimum size fish. Add "expert-only" to the equation and the fish is in trouble. A lot of people do not know better or go by what their LFS
says "might work".