You may need to call a professional, but your post indicates you are a diy.
When they get in through cinder block, they generally nest in the cinder block holes. I've literally gone through 30 plus cans of bee spray, in cinder block(many times). I've plugged off any other possible entrances, and I unload can after can, until the fumes kill them all.
You mention a new entrance, which is concerning. They should be nesting in the cinder block. If they are not... An 18 inch crawl space is oppressive.. Anything less than 24 inches is...it's possible they went past your cinder block, and nested in the chimney, or the gap between the flu.,. Start a fire. They generally nest close to the edge.
If you plug the entrance, they may start coming in your house. Impossible to know what you've got.
Good news, is that if you have cold mornings, you can track them down with cold temps without fear... Kill them when it's cold...
I'm a degreed computer programmer, but I preferred working at a utility. I kill them every day. Have some allergic guys, so I like to go when it's a big one... Have another guy with a Entomologist degree, that also worked as an exterminator for years. He's only referred to as "Bug Man". Never steered me wrong, as far as Diy, killem all, at work... I can forward any further questions to him...
If they're not too clever, you can kill them on your own. . But please note, that I've had to unload $100 worth of bee spray, for the big Cinder block colonies... Your kidding yourself if you think 3 or 4 cans will work. (Assuming they are in the Cinder block)
Good luck..