Need medical advice ‼️‼️‼️

Leah

My babe Chase is 10 weeks old today. A week ago 2 days after his first round of immunizations he had a bout of not holding anything down and he got pretty dehydrated so I brought him to urgent care and they were talking about doing an IV of fluid but he held down 4oz of pedilite so it wasn't necessary. Anyways, all week since he's been different like really sleepy and more fussy than normal and his soft spot is STILL caved in. A decent amount. He has a head full of hair so I can't see it but I can definitely feel it. Right now he's so tired and his lips are dry and his soft spot is sunken but he's holding everything down and eating. I already called the doctor and brought him in a few days ago but all they said was he's fine don't worry. Well I'm worried. Could there be something theyre missing? Is this normal? I'm worried! If I bring him to the doctor again they're just going to say it's nothing but I'm wondering if it could be something else, I don't know im a first time mom but this just doesn't seem normal to me. He is wetting diapers a lot and pooping a lot as well.