Stomach pain after eating apples

I do have terrible burning stomach pain and cramping after I eat an apple. Not anything added to the apple, not a caramel apple, but just a normal apple. I noticed pectin mentioned in some articles as I've been doing my online research about Fibromyalgia. For some reason, today it hit me that I should look up stomach pains after eating apples, and I found out about Fructose Intolerance. I have been suspicious that I have food intolerances for some time now, but this is driving me to look further into it. Here's what I found -- from a doctor's notes regarding a patient who also had Fibromyalgia:

"The patient's lymphocytes have shown a deficient ability to tolerate fructose (found in table sugar, corn syrup and fruits). Fructose is metabolized differently from other sugars. A fructose load leads to accumulation of fructose-1-phosphate in cells which may partially deplete intracellular ATP levels in susceptible individuals. Decreased cellular ATP causes disturbances in protein, DNA & RNA synthesis, interferences with cyclic AMP formation, and reduced ammonia detoxification. Several forms of hereditary fructose intolerance have been described. Symptoms may include fatigue, headaches, weakness, dizziness, behavioral changes and depressed immune function. Excess intake of fructose should be avoided, rather than absolute removal of dietary fructose. Whole foods containing fructose (fruits and some vegetables) may be consumed, in order to benefit from their overall nutritional value. Foods very rich in fructose include table sugar (sucrose), high fructose corn syrup, corn syrup, fruit juice concentrates and a large list of prepared foods containing sucrose and/or corn syrup. Reduction of excess dietary fructose intake by avoidance of foods very rich in fructose is suggested." [source]

It's a pretty good website for Fibromyalgia tips, but keep in mind the author of the website is a rep for a vitamin company, so there is some attempt to sell you products (completely fine and legal, I just thought I would let you know that right off the bat)

The Livestrong website substantiates what the doctor says about Fructose Intolerance here