My granddaughter and my daughter both have had that test. They later both had skin prick tests to confirm the results. My granddaughter was a baby and only drinking formula. When my daughter switched her to a non-dairy formula, her eczema was better and she was less cranky. We never gave her the other foods to which she tested allergic. One was eggs, another peanuts. I don't remember the others.
When she was around 5 or so, her mother gave her scrambled eggs for breakfast and when there was no reaction continued to give her eggs. She had always eaten baked goods that contained eggs as well as cheese without having any sort of allergic reaction. She still eats eggs.
When my granddaughter was in the first grade the cafeteria gave her juice instead of milk. She took it upon herself to pick up the milk carton and started drinking the mild too. After several weeks she told her mother she was drinking the milk. Since she didn't have any obvious reaction we took her to the allergist who then used the skin prick test. Results were that the only food she was then allergic to was peanuts. She's still allergic to grasses and pollen. She had a severe reaction in the form of asthma to pollen this spring when she played in the piles of blossoms on the ground.
I strongly urge you to try removing, for several weeks, all the foods to which he tests allergic. What happens for him and what has happened for others may not be the same. Each of us has our own body chemical make up.
In an answer for a post asking about when to give peanut butter to their toddler, a mother answered that her daughter immediately reacted with major swelling including of her airway. They were fortunate to get her to the hospital in time to save her life.
I have numerous food allergies. My allergic reactions become increasingly more serious when I continue to eat a food to which I'm allergic. For example, I'm allergic to chocolate. I love chocolate and do eat it from time to time. The first day I have a few bites, I feel OK. The next day, my stomach feels a bit queasy. If I continue eating it I feel more and more nauseous to the point I have to stop eating it. I've never vomited but then I know when to stop. I do feel some concern every once in awhile because I could have a really serious reaction tho it's unlikely.
I'm also allergic to peanuts. I do not fool around with eating them. People have been known to go from a mild reaction one time to anaphylactic shock the next week or even year when they eat one peanut. Because I've lived for several decades with this allergy I'm not as conscientious about reading labels as perhaps I should be. We are conscientious to see that what we buy for my granddaughter does not contain peanuts.
Food allergies cause a lot of havoc in our bodies. They are not something to fool around with. What is wonderful is that often children outgrow their allergies when they start in early childhood. I do suspect, however, that if the child continues to eat the offending food it's possible that their body will build up an intolerance causing the allergy to continue. An allergist is the best person to ask about that.
My reaction to food allergies are two fold. Upset stomach and/or hives. I found that I feel noticeably better when I stay away from the foods to which I know I'm allergic and to the ones to which my body is intolerant. I'm no longer concerned about making a differentiation between the two. As an adult, I'm able to know how my body feels and judge the effects of certain foods. A toddler cannot do that tho you may notice a difference in the way he feels and thus behaves.
Also, it often takes several times of eating or not eating a food before you'll notice a difference. I hope the doctor told you how long you should wait before introducing or reintroducing the food.