I cry everytime when I have to put him to sleep

I love my baby more than anything, but I cry every time when I have to put him to bed. He doesn’t want to sleep so first he fights every sleep. I have to cradle him to sleep and after that if I put him down, he wakes up immediately and I have to start all over again. During the day he even wakes up after every 30 mins. He was never like this 2 weeks ago, but since he’s 19/20 weeks, he is really attached. I can’t do anything and the problem is that I am starting work tomorrow.. not sure what I want to achieve with this post.. I am just hoping that someone has tips or anything..