Advice needed......

My son had his 14 month check up today, based in the UK, and was told although he had gained weight and length he has dropped centiles therefore we are being referred to a paedeatric doctor at hospital, anyone experienced this and any advice please, absolutely beside myself with worry and cant stop crying πŸ˜­πŸ˜”πŸ’” he is 20lb 13oz and 75 cm