hey guys, i would really appreciate if you can help me..
yesterday i drove my truck (very easy on it, seriously) like 1-2 miles around town during the day and everything was perfect.. I parked my truck and at night I went to the gas station and I could hear a "not loud" rattling noise in my engine and I thought the lifters were the ones causing that noise.. I talk to some people about that and they told me it was OK for me to drive the truck like that till I bought a good set of lifters, well I fired my truck today in the morning to take it to the mechanic to take a look of the noise, and it looked like something was loose INSIDE the engine, it is a noise like a metal is broken on the inside.. very LOUD.. what do you think it could be??

thanks guys in advance..