Data used in Background and Battery Drained

Hi bro, I charged my phone to 84% and started using it and faced heavy heating and massive charge drop, then disabled WiFi and connected to mobile internet, and shockingly mobile net 2.5 gb was consumed in 30 mins without using anything, I thought it might be any software update dowloading behind and there is nothing like that because already it is is latest software, what might be the issue you think bro?