Two carpros

Hi, two carpros. I have a honda acc 08, 4cyl Ivtec engine. Last year I hit the sump againgst a rock, and the engine oil drained out when I was on high way speed. I immediately filled it with another oil; suddenly I do notice a clunky kind of noise at every cold start-whether mornings or evenings, for a while before the noise stops; and have notice that when I step on the gas, the car seems not to respond and stalls at slow downs. I took it to a mechanic and he said it he needs to adjust the valves. He did adjust the valves as he claim, but the clicking noise coming from the valve train area seems to be there. I have noticed that after what he did, there is a loud noise that comes from the exhaust pipe as an exhaust leak, and the car misfires. I have inspected the car for exhaust leaks, and found none. My scan tool retrieved two codes-P0302 and P0103. I have changed the air filter, plugs, cleaned the injectors etc. I want to inspect the valve train myself to see whether the camshaft or valve tappets were not properly inspected by the mechanic. What is your advice please.