Yes, you have a major leak somewhere.
Before you do anything, turn off the tank valve, remove the regulator coupler from the tank, and see if you have a gasket inside the coupler or not. Then check the condition of that gasket, because there are single-use versions as well as long-life reusable versions.
If you get through that part, reattach the regulator to the tank, turn the regulator fully counter-clockwise (to zero), then turn on the tank valve.
Mix up some dishwashing liquid and water about 50/50 and brush it over both ends of the regulator coupler (tank end and regulator end), and brush it over the stems for your regulator gauges. If no bubbles show, turn the regulator up to 30 psi, and brush the outlet of the regulator and any shut-off and/or check-valve fittings.
Then work your way down the gas line to the disconnect, and when you get there, dunk the disconnect in a bowl of water.
If you get there without finding a leak, lock the keg lid tight, put the disconnect on the keg, flip the whole thing upside down and dunk it in a bucket of water.
If you didn't find a leak by the time you get through this, your regulator must be leaking out of the body somewhere...
Cheers!
[edit] One item I forgot: some CO2 tank valves will leak around the stem packing unless you open them all the way to the stop. So while you have your soapy water mix, when you get to the "open the tank valve" step, brush the valve stem, too...