Chevrolet Repair: 2000 silverado oil pressure, losing coolant, coolant leak

Question
i own a 2000 silverado 5.3 automatic. first, it seems that i am losing coolant somehow but its not leaking on to the ground anywhere and doesnt look like it is leaking into the oil at all. also i changed my oil about 1000 miles ago and when i checked recently it was about a two quarts low but my oil pressure still read 40 and 50. but then when i added one quart it is now at 55 and at 3000 rpm it is a little over 60. do i need to be concerned about any of this. and what could be the cause of that?

Answer
Sorry for the delay my dad had a bypass surgery on Tuesday and I am just getting to these messages now.

 Find the coolant leak and fix it.  If it isn't coming out the bottom or going into the oil then pull the plugs and inspect them. Check the waterpump seal and corners of the intake for small leaks.  They can leak out slowly and evaporate before it hits the ground leaving behind the coolant stain.

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