Before you call a pro, there are a few things you can check easily.
First, look for anyplace that the system spits a bit of water when the pump shuts off. That is a classic sign of an air leak.
With the pump running, look in your skimmer and check that there isn't a whirlpool showing up and that the skimmer isn't making any noise. Make sure the weir is laying below the water surface and that it can move up and down freely.
Shut down the pump and remove the pump strainer lid and inspect the O-ring for cracks or distortion. Lubricate the O-ring if it is good, replace it and lube the new one if it isn't. Reinstall the lid and be sure you get it tight.
Remove the strainer basket drain plug and inspect the O-ring. Same deal as the lid O-ring. Lube and reinstall, with a new O-ring if needed.
If those efforts don't fix it, get your garden hose with no nozzle and watch for bubbles in the basket while flowing water over the pump inlet joint and any valves or fittings on the inlet plumbing. If the bubbles reduce while you have water running on something, it is probably leaking.
If none of that shows a problem, before you call for help, I'd try digging down to where the pipes that come from the pool to the pump inlet go into the the ground. The very first elbow that will probably be a foot or less underground is a common source of leaks. You should see dampness around it with the pump off if there is a problem.
Another possibility is that you have a restriction of some kind in your plumbing on the inlet side. Toys, rocks or leaves can cause bubbles in the basket. If you have a drain and skimmer both, try closing each to see if the bubbles are better or worse on one or the other.