My 9 month old has come out in hives / welts across his body on and off over past 2 weeks. Went to GP on Monday who gave piriton and they went down alot immediately so definitely an allergy. GP said to try and work out trigger and use pititon on ad hoc basis. Since then we have gone back to a basics diet giving things we know he did not react to when first started on solids, but we don't really know how long to wait between introducing foods, or indeed if it is even external cause eg grass pollen as seemed to come up after crawling outside a few times. We are keeping a diary - how long would we expect a reaction after giving new food / trigger? ie how long wait before introduce next new food? He has new hives today after having porridge oats mixed with water - could this be the gluten? He has always been a baby who glugs his milk and has from time to time projectile vomitted feeds but never seemed ill afterwards and generally a very contented baby. He has excellent weight gain which does not seem to fit with gluten allergy. Normal bowel movements eg not loose. We feel we have been left with lots of questions and not sure where to start in figuring this out. The welts were worse where his nappy was - can pressure on the skin aggravate the hives? Any advice on this welcome.