D.B.
It definitely sounds like autoimmune, doesn't it? These things don't usually show up on MRIs and other tests. It sounds like everything is really out of balance - could have been triggered by the pregnancy but it could also have been building for a long time. These epigenetic changes plague a lot of people. The menstrual issues, constipation/intestinal problems and the skin problems all speak to the systemic imbalance and the body's desire to get rid of these problems (through the skin, through elimination, etc.). I'm part of a large network of people working with problems like this, and I'm honestly not sure that it's specifically postpartum. We see so much of this and, for some people, there's a trigger, but for others it's just coincidental or the result of a lot of factors. I don't think it's in your head at all. I think it can have an affect on your head, mind you, but based on my experience, it's very real. There are things you can do to boost your immune system that are based on solid science and the epigenetics field (including the most heavily researched, safe additions to the diet). So I'd say there are other avenues to be pursued before giving up, before any more tests (since you have no answers anyway) and since the MD is almost throwing up his hands and saying it's psychological.