Need help

[Eric98Stang]

Alright so I drove home from work aprox. 15 minutes got home changed my shirt and went to the bank turned off the car. went inside to draw money came out went to crank up the car and it turned on then struggled as it sat in idle. the temperature gauge was nicely in the middle but my engine oil gauge was at the H and idk why, so I drove home and you could hear clicking in the exhaust pipe probly close to the y pipe and it got louder as i pressed the gas. got home popped hood and there was light grey smoke coming from the engine. any Ideas on what the hell this could be? anything helps people i would appreciate it greatly