Why is the lamp shocking when the light switch is off?

Hello. There is an upper ceiling lamp in the corridor of a panel house apartment. After buying the lamp, I tried to connect it myself. The switch was turned off, but the current jerked. An electrician was called up who connected it, but it seems the problem itself remained. Today I wanted to put in LED lamps, I screwed one, and when I began to unscrew the second, the LED lamp lit up. If you screw in the second lamp to the end, it goes out and that's it when the switch is off. Lamp with 2 lamps.