HELP! 8 month old will not sleep!

My son was sleeping a normal amount around 7 months then I started a new job 5 days a week and he stopped sleeping. I've since quit my job bc he wasn't adjusting well with his sleep or with a new babysitter. We're going on a month now and we are both exhausted, I feel like I have tried everything!! He will still take 1-2 normal length naps a day, anywhere from 1-3 hours at a time which is the same amount he was napping back when he was sleeping through the night. He will go to sleep around 10 and wake up around midnight or 1am and be up ALL NIGHT. I have tried putting him to bed earlier, a night time routine, feeding him more throughout the day, giving him an extra bottle and oatmeal before bed, rocking him back to sleep, everything. His doctor says its separation anxiety bc it started when I started the new job & for a while he would sleep in his crib if I laid in the floor next to it, he would peek over the side every now and then to make sure I was there but he was fine. After a few weeks he wouldn't even do that....I went as far as moving his crib into my room so he could see me. He cries and cries then if I put him in my bed he kicks and laughs like he wants to play. Last night I finally rubbed his back until he fell asleep then 10-15 mins later he jumped all of a sudden then started rolling back and forth whining then crying again so I rubbed his back and he fell asleep but this process kept repeating. I've even tried letting him CIO and he just cried until he threw up and never fell asleep. I'm at my wits end and OUT of ideas!!!

I don't work outside the home so I don't know anything about separation anxiety. Does wake up to eat? Well I first got DD to sleep all night at 6 months I would rock her back to sleep with a pacifier, her ped said she didn't need to eat. It took a long time of screaming an crying to get her back to sleep. I would walk around and bounce her bc she wouldn't let me just sit in the rocking chair. I did this for a week and it worked. Until she got sick for the first time at 71/2 months and was up coughing all night! So I started it again when she turned 9 months but she won't take the pacifier anymore. I would get her back to sleep once or twice but then as soon as I lay her down she screams again. So I haven't been able to get her back to sleep without the bottle but she sleeps longer every night before waking up.