High needs infant, toddler acting up

My son is 8 months. He needs me ALL the time. In a normal day he cries a lot, has to be soothed/nursed to sleep, and he refuses solids so I’m basically bed bound a huge part of the day. And in turn, my toddler is acting up. Screaming for everything when prior she would use her words. I’m going nuts with the two of them. On top of that my toddler is beginning to be mean to her brother. Any advice from anyone who has been there, done that? It sucks because I’m alone a majority of the day and evening, so I don’t have help.