We had reviewed your site and found that jquery is making trouble while extending menu. So we request you to check by deactivating every plugin and check if problems still persist. And if you had done customization of theme then please check for function with prefix MM, this plugin is creating error on console.
It seems you are using obsolete version of encounters ie 1.6.7, we are already on to version 3.0.0. Please update your theme to latest version.
Note: Please take a back-up of your whole site so you can take immediate action when disaster occurs.