Post #12 is a great suggestion.
If you end up with everything apart:
1) Run your fingers along the inside of the tires, and do it both directions. If you find blood and pain, there is something there.
2) Do the same with the rim, look for spoke punctures or bulges in the rim tape, and feel for shears along the exposed metal.
3) check your valve stem hole for jagged spots. punctures can happen there too.