Hi Caramella, it more sounds like separation fear. Newborns don't understand that them and the mother are two different person. They only start to realize it around 8-9 month old. It is natural. It could last until 1.5-2 years. Kids normally become very clingy and some of them cries horribly if it is not the mother carrying them. But there are a variation of reactions. Again, it is natural. It will pass.
jealous is normal. My daughter was very innocent till her baby brother came. She changed suddenly when she saw her brother. I spoke with PD. I was advised to be with her while someone else took care newborn