Tantrums at bed time/sepporation anxiety?

My bub is 9 months, he used to go to sleep alone for every sleep, he started crawling last week and im unsure if its related but since then he REFUSES to go to sleep alone, he starts crying hysterically as soon as i put him in his sleep suit and bawls his eyes out when i put him in his bed, he can go on and on, until i have no choice but to cuddle him to sleep, if i put him in his bed before hes fully asleep he starts to cry as soon as he feels me putting him down, any tips? Is it just a phase? My other 2 never did this...