My 5 year old son was stung by yellow jacket last night 4-5 times (one looked more like a small irritated pore as opposed to a sting but he claims it was a sting). Stingers were scraped out, area washed, ice applied. No severe swelling . Today he began vomiting. Severe vomiting with stomach pain. No fever , just very tired and and can not hold even water in his stomach. Is this an allergic reaction and should he be seen by a doctor? If so, how soon?