Help! 2001 loud engine knock

Last Sunday, hopped in camaro & drove about 150 mile round trip without checking fluids. Usually I only use car to travel back & forth to work about 20 miles round trip. While driving I noticed I had low oil pressure, gauge showed about 40 usually at 60, other than that no problems on trip. Checked oil and saw I was a quart low, added a quart and all seemed well. The very next day I started up car and there is a loud knock that appears to be coming from top of engine on driver side, knock rate increased when engine rpm increased, can’t quite tell, but it sounds as if it is coming from top of engine on driver’s side. The knock went away after about a minute. This has been going on all week sometimes there is a knock for a few seconds, and at other times it continues until I arrive to work about 15 minutes later. I am due for an oil change which will happen in a couple of days. First question is it safe to drive or will I screw my engine up? 2nd what might be the problem? Thank in advance for any help.

What engine do you have?

3.8 V-6

The LS1's are known to have piston slap, I don't know about the 3.8, sorry.