i need help on this

Hi guys, can i just ask something. I’m living with my in laws & i have my nephew who’s about 3YO staying with us too as my MIL took care of him since he was a newborn. No doubt, I love him really. Just that I wanna ask if it’s normal to not like his attitude at times? He’s still not able to talk fluently and I’m not sure if he could understand what I’m saying. I have a 3MO baby with me, I love that he enjoys to play with my daughter however he kept falling sick almost every month he will always fall sick either down with fever/running nose/cough or all in one shot. He still gets around my baby even though I stopped him, especially when I’m feeding i can’t move around much, he’ll get on top of the sofa/my bed and get around my baby. Comes to my room or sofa whenever i’m with baby full of his cars/trucks toys and then climbs up my sofa jumping around. My MIL didn’t even bother to like “ure sick come here” and take him away. She just let it be you know. She have a very LOUD LOUD LOUD LIKE SUPER LOUD VOICE, when she talks ITS LOUD AF looks like as if she’s SHOUTING. oh and, i take care of my kid 100% at home without NEEDING a single help from her. My baby may not be able to sleep properly sometimes because of my nephew who likes to throw toys around/my MIL being very loud. But she blames me sometimes because of not swaddling my baby. I’ve tried whatever I could to swaddle my daughter but she can’t sleep in peace with being swaddled since she was a newborn. I only swaddled a month plus and that’s it. I can’t lock the room or close the door everyday even though my daughter is sick because my MIL will say “pity your daughter, always in the room. sit outside lah have fresh air what.” sigh. what should I do guys? How do I say that ok he’s sick and I gotta put my baby in the room, i do not want him near my baby. But at the same time I feel so bad because he always love to play with me or baby.