An air lock can cause some problems similar to what you describe in your submersible pump. To get rid of this start and stop the pump recurrently. It's worth a try. Something more serious.... get a tech pro buddy!
Check the ball valves and the ports of your pump properly. They should be clear. Submersible pumps are notorious for developing problems in these parts. If they are not clear change them.
Is the voltage supply steady and correct. Get that checked. If it's not right correct it. your submersible pump will have a pressure control box. A defective pressure control box or it's wiring can cause the problems. Simply get it replaced to get your pump working again.
Your pump may have a air leak somewhere, check all of the connections by placing your hand around them. If you place your hand over the leak you should hear a change sound the pump is making. You may also need to prime the by filling the intake with water.