PYLORIC STENOSIS - Has anyone had a bub with this diagnosis?

DS is a month old and has not been holding down feeds for a week. Started of as just a wee spit-up but ramped up to the projectile vomitting. He has lost almost 1.5 kilos - praise be for huge gains in the first 3 weeks - and is now back at birth weight. After numerous CHN, GP and ED visits they have narrowed it down to possibly be Pyloric Stenosis so now we are just waiting to have an ultrasound on his tummy tomorrow to confirm PS or not. So has anyone else had experience with an infant who has it? If so please reassure me that everything will be fine - the idea of my wee little man going under the knife has me in a panic!