Those dreaded food allergies

Auggie has been doing so well eating just about anything I dare give him. It's hard to resist giving him something when he sees it on my plate and just has to have it - sushi yesterday!!  I have to stop and remind myself that we are probably dealing with multiple food allergies that have yet to be confirmed.  Yesterday he started getting a little blotchy after drinking some vanilla rice drink, I didn't think much of it as he often gets blotchy after napping and rubbing his face.  So, I gave him some again today - by this evening he had swollen, red, itchy wrists, eczema on his back and red blotches on his face that extended from his mouth to his eyes.  He was also very cranky and did not want to eat.....I immediately scanned the ingredients on the rice drink and found that the only thing in the rice drink that his regular hemp drink does not have is "sunflower oil and/or safflower oil and/or canola oil".  He 's been eating canola oil for weeks so that's not it.  Could he be allergic to sunflower or safflower oil??? What else could it be??  We'll cut out the rice drink for now and see if his skin improves.