Has anyone's LO stopped growing in height and dropped on the charts but maintained their weight? Was there a cause or did they eventually catch up?

DS just had his 2 year and he is only 5th percentile for height on WHO. He was measured laying down, using a measuring device attached to the scale and not the drawling on paper method. He was also measured twice (first time had him at the 3rd). He was 17th and 34th percentiles at his 18 and 12 month appointments, respectively. I have been noticing a steady decrease in height for some time. At this point the pedi did not seem too concerned but wanted to check where we were at in 6 months. He said he could have just slowed down since we were coming out of the cooler winter season. He did say that if it was his nutrition, since he is on a limited diet, you would expect his weight to drop first, but he has always been consistent fluctuating slightly between 75-85th percentiles since birth. I am worried because of his FPIES and possible EoE diagnosis. We are also dealing with sleep issues. CGD does run in my family (brother and his children) and my MIL is Japanese and very short so it could be genetic.