Food Allergy?

So, our 6 year old son, Camden, suddenly started having a bad pain in his stomach 4 or 5 days ago.  It comes and goes, so he will be acting totally fine, and then later he will be crying in pain for quite a while.  He says it hurts on the inside, and it's also sensitive to the touch.  Sometimes it is after he eats, and sometimes it's just in the middle of the day or he will wake up in the night crying.  And it’s pretty bad – the poor little guy just sits and cries, and refuses to eat or drink while this is happening (and for those of you who know Camden, you know that refusing to eat means he’s seriously not feeling well).  He hasn't thrown up, had a fever, or diarrhea – just the pain in his stomach.  Oh, and it’s just Camden – none of his brothers have been sick at all, so it’s not very likely that it’s something contagious.  

I would think it was just some GI bug, but on Saturday the front of his ankles and tops of his feet were bright red and looked like a bad sunburn (but he had previously had on jeans, socks, and shoes so we knew he wasn't burnt), then that went away.  Then Sunday his face looked puffy, especially his cheeks and under his eyes.  And this afternoon his face looks a little red with small dots, possibly like hives.  I asked Michael what could cause stomach pain and skin problems, and he said maybe it’s a food allergy.

We keep waiting to see if maybe he’s just sick and he’s going to get over it.  (And he had last week off of school for spring break and his school has this week off too, so we don’t have to worry about him missing out or anything).  I thought maybe he was getting better yesterday because last night he slept all night without crying or coming in to sleep in our room for the first time in 4 nights.  But then today I took Kolby for a doctor’s checkup and Camden went with my mom to institute and then they went out to lunch afterward, and after lunch my mom called to tell me he was crying and crying in the car.  They came home, and he calmed down after a while.  And now he’s acting totally fine again.  But now I’m wondering if it really is a food allergy.  The idea makes me sad for Camden – the idea that he may always have to be careful about finding out what ingredients are in foods at home, friends’ houses, and restaurants for the rest of his life.  And it could make it harder to plan meals for the family.  Of course we’ll do what we need to do to fix this problem for Camden, but I can still cross my fingers that maybe it’s not really a food allergy, right?  

None of our kids have ever had any allergies, and neither have we, so we’re new at this.  I’ve left a message for the pediatrician, but I’m wondering if we go in and he’s not having any of the symptoms at the time of an appointment if she will be able to make a good diagnosis.  (Do food allergies really come on all of a sudden like this?  I thought since our youngest is 4 years old the boys were all past the stage when an allergy would have shown up, and we were lucky enough to be allergy free).  And if she does think it might be a food allergy, are we just going to have to keep track of all the foods he eats every day and try a process of elimination to figure it out, or is there some kind of test that can tell us for sure what is causing it?  Or maybe we’ll go in and the doctor will think it’s something else entirely.  I guess we’ll just wait and see.  But hopefully we can get him over it before too long, poor little guy!