Is there a way to check where pipes are leaking under a concrete slab without digging everywhere?:(

It depends. Let's find out what type of leak that you have. To check to see if you have a hidden pressure leak first shut down everything in the house, no flush, no drinks of water, and if you are on a meter go out and check the little pointer in the gage. It should not move or creep. If it does you have a leak. If you're on a pump then check the pressure gage after the pump builds up to pressure and shuts off. The gage should not fall and the pump come back on. If so then you have a leak.
Let me know what you find. Good luck, tom

Yes, there is. First, do as Tom said. Then, go to Yellow Pages and find "Slab Leak Detection Company" under Plumbing. They will come, listen to your slab and tell you where the leak is. Expect to pay about $300.00 for the service.