8 month old not sleeping through the night... any tips?

Okay so my baby boy is 8 1/2 months. Since he was 3 months up until almost 8 he was sleeping perfectly fine throughout the night. I have him sleeping in his pack n play. Well around his 8th month mark he started waking up throughout the night. At first it was once or twice, but now it is constantly. He'll wake up at least every hour, give or take. I make sure he is fed, changed, I'll give him gas drops or tylenol if I think it's from teething or gassy. I make sure everything is okay. But he just continuously wakes up crying. Then as soon as I pick him up he lays his head on my shoulder and goes back to sleep. I cant tell if this is a sleep regression or if he is starting to get clingy. I'm thinking clingy because the past 2 nights I put him in my bed and he slept the whole night... I know bad habit, but honestly I need the sleep. So my question for you mama out there that have gone through this, do you have any tips for me? I really dont want him getting used to sleeping in my bed, but me and my hubby both work and not getting sleep has really been taking its toll on us.