There's a simple trick to finding what has created the puncture. Take the tube completely out - trying not to rotate the tyre at all while you do it. Pump the tube way up and find the hole, often you can hear the hiss or sometimes the air blowing out from a little puncture can be felt blowing on moistened lips.

Having found the puncture you can then align the valve up with the valve hole in the wheel rim and feel carefully inside the tyre where the tube hole is (you will likely have forgotten which way around the tube was - so there'll be two alternative places to look, flip the tube side to side)

Sometimes you have to fold the tyre into a bend to open up slashes to find small bits of embedded glass.

This is a frig, but will what is effectively the same puncture coming back.

OR

get Marathon + and be done with it.