1988 s10 blazer top end noise
 

ok so i accidently let this 4.3 v6 go low on oil and now the top end is slapping/tapping. i have oil in it, it burns oil, also leaks but has always ran really freaking quiet until now. how do i know if my oil pump is bad? could it be a bad filter? my oil pressure hasnt dropped that much but i still noticed its not as it was before, just a little different. im thinking about taking the cover off and dropping some oil on the top of the rockers and thats pretty much all i can think of doing, and i raelly dont have the money for a mechanic to look at it. help!