I charge my iPhone on my macbook pro 15", 2014, when I go to bed. Recently and every time, for the last couple of months, it connects and disconnects rabidly, about every half second, and after about 15 seconds just stays on disconnect. This does not happen on the the right side USB and I've tried other iPhones and lightning cables and it does it to all. However, any other USB device works fine. Any idea what the heck is going one? I don't want to take it to Apple if it's a minor issue. Thanks.