I agree, I'd suggest finding a Functional Medicine Specialist and getting the Metametrix GI Effects Stool test.
Tough to say what all you have going on, but from your chronic constipation symptoms, stomach pain and skin problems I would guess:
-bacterial overgrowth dysbiosis
Your vegetarian diet is definitely not helping things. Due to the issue, your not absorbing vitamins and minerals and are obviously low on muscle meat protein.
Lots of people here would tell you to start out by doing a colon cleanse, then moving on to other organs.
I would suggest starting out by changing your diet to an organic diet, based on whole foods. Nothing that's boxed, canned or wrapped. Limit Sugar intake and drink plenty of water.
Get the stool test done and figure out what EXACTLY is going on in your gut before you try self treating.
I think curezone is a great site, but there are a lot of whacked out people on here who ARE delusional and have NO IDEA what they're talking about. You'll drive yourself crazy trying to self treat, because you will be just guessing.
So many symptoms overlap with different conditions that's why I keep stressing to get a stool test as Jorge has mentioned.
Good luck and just know there will be better days ahead for you.
Type in functional medicine practitioner in google and find someone in your area. Its not cheap, but will get you on the right path.