I'd suggest that you have a demonstrated metabolism and lifestyle/activity level and likely age (as in you are a young person) that very much ups your need for good carb with every meal. In my opinion, this would look like: At least one potato per meal, fruits whihc which are high starch/much higher carb fruits such as bananas, more than once a day, snacks whihc which include a combo of some proten protein + starchy carb. In your case, I'd throw the "big ass salad" out the window for now and replace it with a much more dense meal, including starchy carbs and starchy fruit aand fat, all "anchored" with protein.
Later addendum: The symptoms you describe could easily be HYPOGLYCEMIA and are infact, highly consistent with what I have experienced in the past. The degree of brain slowing/fog can truly be pronounced. However, this is a peer to peer support board, not a healthcare treament or advice board. But I'd give odds that if you rework your diet as described, you will have an abatement of these symptoms, which, by the way, if they go on and on can become serious.
I'd also suggest that you have the inherent metabolism + age + activity level + history of fighting to GAIN weight that would make you a good candidate for learning about how to prepare some types of grains via soaking etc to render them a healthy part of a diet for you. You can find info on this on the Weston A. Price foundation site. It is true that this needs also to be balanced with your psoriasis picture, so, mamking the other changes first and seeing if they solve the immediate symptom issues would likely be the best route. Then you can do some research.
Your question, in my opinion, is an excellent one to demonstrate exactly how and why "paleo" is a super healthful way to eat, but must be individualized taking into account the above cited factors as well as individual health issues.