My phone overheats in the camera part and it always drain faster

Hi I'm a working student I have a problem on my phone when I recently left it at home when I came back my phone's camera part is very hot and when I charge it's overheating fast when I'm not using it and when I charge it to 100% shut down it for a few hours when I came back open it I can't when I charge it's 0% and my speaker in my phone produce buzzing sounds I tried resseting app preferences it got worse(it works with headset and wireless headset),It also drains much faster when I'm not using it but instead it drains slow when I'm using it why?