Oil Pressure problem

I am new to these threads and I just recently bought this 95' Aurora from a friend of mine who told me this was a good place to go for help. I recently just got my oil changed by Monro and then 2 days later got my Front left wheel fixed. The bearing assembly kit had to be replaced... Now a day after that my car started to say Low Oil, and Low Trans Fluid. Then a little bit later it said "Low Oil Pressure" and the red oil light flashed on my dashboard. My screen was saying my oil pressure was as low as 7PSI's, and was getting about as high as 18PSI's which is much lower than normal.

Any help would be greatly appreciated...thanks

Be sure oil level is full on dipstick, '95 takes 7.5 quarts of oil.
Also engine requires 10w30 oil, a lighter weight(I think) will result in low oil pressure.

I have since gotten a completely new oil change, even know the one I had was only 2weeks old. I got 10x30w high mileage synthetic oil put in my car...

I appreciate it.