Chad,
Not an expert on such things but I don't see any compelling reason why you shouldn't see a urologist to get worked up an see what is going on with your ED. If nothing else (s)he could probably hook you up with some samples so you could figure out whether sildenafil has stopped working for you or whether your off-shore pills don't actually contain any sildenafil.
You might also consider talking to a doctor about
your testosterone levels. There are things that can be done, sometimes, to restart one's natural production and wean oneself off of the synthetic stuff. This forum isn't a particularly good source of information on such things but the topic does pop up from time to time. Look for "Tall Allen"'s suggesion on
this thread for some drugs you could talk to a doctor about
(your primary care doctor might prefer to refer you to an endocrinologist.)
I would'n worry too much about
confiding in a few discrete doctors. Unless you are a sports professional nothing you describe is wildly illegal and confidentiality should protect you from casual leaks.
Good luck.