Fatty acids in circulation are always free as far as I know. A fat such as, say, the sesame oil you ate, is composed of fatty acids bound together. Once the fats reach the small intestine, they mix with bile and then are cleaved by enzymes into fatty acids. Hence free.
There should be free fatty acids in the blood, as far as I know. But they shouldn’t be consistently elevated as is seen in so-called metabolic syndrome and insulin resistant diabetes. The fact that they can be consistently elevated suggests that there is a metabolic disorder. But which came first? The metabolic disorder or the elevated fatty acids? I don’t know, but I am proposing that the elevated fatty acids may have come first. And furthermore, I am proposing that certain types of fatty acids will have that effect – trans fat or elevated omega 6. I don’t know that for certain, but it’s an educated guess.
In any case, unless you had really bad glucose control (and you don’t if you haven’t been diagnosed with diabetes, I would say), sugar shouldn’t produce neuropathy. But perhaps there is a link between high omega 6 and neuropathy in your case. I don’t know. But sesame oil is high omega 6 pufa.
Also, what the heck are you doing eating a salad? From what you’ve described, you need lots of calories. Salads don’t tend to provide that. And also, when digestion is weak raw vegetables are typically some of the worst things to eat. Typically, to get digestion on track, you’ll need a) lots of calories (as in, think 4000 calories a day range), b) lots of carbohydrates, and c) adequate quality protein. Oh, and enough salt too. If you are missing any of those things, you’re going to have a damn near impossible task set before you. So salads aren’t really good candidates. Think more like rice, potatoes, ice cream, bread, cheese, butter, pizza, pasta. Not raw vegetables.