Help: it says 'usb to charge' but charger or usb not connected

hi, as it says on the title over the last month i have what i think it is a software error. Sometimes if i don´t use the phone for long periods a time, on the notification bar appears as if i have the usb connected but i don´t. This also hits my battery because it doesn´t let the phone enter the doze mode, on the battery stats says 'android os' and when i look at the activity it says the phone was active even when the screen was off. I´m worried about this and i need help. What can i do? Sorry if it´s hard to understand, my english is rusty