| generally- need to stablize the bass with taking any pressure off of the cracked area and of course keep it in a stable humidity and temperature. Without pictures, this is about all I can tell you about what to do-But, may I share with you something I learned the hard way(that is, it took more than one crisis event to teach me that I could prevent a lot of the stress associated the wonderful life of the double bassist---If I would prepare for them better)
It seems inevitable that this(crack or open seem) will happen soon or later to carved bass owners. I doubt that there is a bassists participating in TB who hasn't experienced a crack or an open seam if they have been playing 5 years, or probably less.
I advocate to all bassists that there are a few things that we should carry in our gig bag or bass mobile -liquid hide glue, couple of rib clamps, duct tape(used on top of painters tape to prevent damage to the varnish, and even painters tape will damage it if it is left on too long)a sound post tool, a grabber thing that mechanics use to retrieve something like a spark plug(I think cars still have plugs), extra strings, machine oil,extra bow, a small drop light with an extension cord.,needle nose pliers, shop towels, super glue, knife., bungie cord to secure bass, pillow for neck.
Overdoing it? Perhaps. However, if I go to the trouble of Practicing(sometimes) getting my bass to my bass mobile, drive maybe 150 miles to a rehearsal/concert, and on the way I hit a pothole or bump the door on the way in, and the sound post falls, then I want to be able to fix it on the spot. My opinion, my experience- A bassist survival kit would make a good gift. PM me if you need to know where to some of these items.
Sorry Future-this is good therp for me after patching cleats all day. with lots of bass luv. | 
CRACK!!! 
