Anorexia? Constant lack of appetite, vomiting...

I'm a 21 year old male, 5'10'', 145#s.
For the past 6 or 7 months I have had no appetite. What I mean is, I'm physically hungry (my body/stomach is telling me I need food) but I am not motivated to eat. Typically, no food tastes good and I have to literally force myself to eat. Its difficult to swallow and I have to constantly stop myself from throwing up. About once a week, I actually vomit soon after finishing eating. I don't feel sick or even nauseous, I just throw up. And I feel find afterwards. When throwing up, my stomach usually empties. I'm making sure I'm not getting dehydrated.
I am currently on an anti-inflammatory, but I've only been on in for about 2 months, and I've had these symptoms before I went on it. I also started taking Accutane three days ago, so I know it's unrelated to that.
I have been to the doctor several times for blood tests and everything came back fine.
I have not lost any weight, but I am unable to gain weight. I sustain myself by drinking protein shakes because I am able to keep these down and they are relatively high in calories.
I am in great shape, I run daily and lift weights at the gym. I have had this exercise routine for several years and I have not increased the intensity or frequency. I have also taken breaks from working out to see if the condition quits, but it has not.
I want to be able to eat like a normal human being again.
Thanks for all the help/input.