I bought a 3 piece suit from eBay. I am noticing the vest is fitting weird. It bunches up around the back of my neck and seems too short in the back. I am unfamiliar with vests, other than owning a few that fit well. What is going on with this vest? The bunching around the neck, almost like a divot with fabric at the base of my neck. It’s like it is riding up. If I lean back in it the problem does not appear...however I cannot walk around like I need a back brace. When I stand-up up straight it is almost like the vest is riding up. Not sure what is going on.