OP, when you say you and your partner have had "all the tests under the sun", could you please clarify? I am assuming you have had semen analysis, day 21 progesterone, day 2/3 FSH/LH, and HSG or similar to assess tubes? In any case, that is what we have had, and are currently awaiting IVF (NHS).
The reason I ask is that I have been obsessing over [[http://www.bmj.com/content/337/bmj.a772.full?sid=e559c358-0fe3-47fe-95ef-973f3d0d37fa
this article]], which includes the following:
"Basic fertility investigations including semen analysis, confirmation of ovulation, and tubal patency testing using hysterosalpingography find no specific cause of infertility in about a third of these couples, who are given a "diagnosis" of unexplained infertility. Underlying mechanisms could include cervical, uterine, ovulatory, peritoneal, immunological, or fertilisation defects. Therefore, the true prevalence of this diagnosis will depend on the range of investigations available at individual centres and the willingness of infertile couples to undergo extensive testing."
I'm sure you can see what I'm getting at: "unexplained" is not a diagnosis. It just means the docs haven't found a reason - usually because they haven't tested for "everything under the sun". I certainly haven't been tested for all of the things mentioned (i.e. cervical, uterine, ovulatory, peritoneal, immunological, or fertilisation defects).
I tend to approach things very scientifically, so am of the view that a battery of tests is more likely to lead to finding a solution than having my feet fiddled with or drinking cough medicine would do!