Right now is the time to set the standards on control. he is totally at that age. Do whatever you need to regarding pain issues for teething, belly etc, but escalating crying when you walk away etc is all about control. Beware of being "too psychological" with infants. They need simple scenarios to learn the next steps, don't worry about psychology until later, when you know everything has been clear and supportive as far as their basic needs from the beginning. He may be having a rough time due to very early bonding (I'm adopted and know many adopted kids) but the same rules apply, and though it can be tougher, it will pass. He is young enough.
MOST IMPORTANTLY, Yes, give him more love, more attention, etc, BUT NOT BECAUSE HE"S SCREAMING ANGRILY. That should be the time when you do NOT reward him with holding and carrying etc, or you will be VERY sorry later. He will learn to scream whenever he is hurt (as in, hurt that you are not picking him up immediately or have left the room) or wants something. Carrying him around all the time or getting a sling because you're scared he'll cry is a recipe for disaster.
My son is ten months, and he's just starting to voice disapproval (angry screams rather than just hungry or tired crying) when put him down at certain times or put him in bed and walk away. I NEVER give in to that. I give him tons of affection if he gets hurt, or is tired or hungry etc, and I MAKE SURE to get over there and cuddle him and join him playing when he's being quiet. Not easy, because it's easy to tune him out when there is peace, but I'll go make a big happy celebration out of him being happy on his own and make sure to give him tons of sincere affection for no specific reason all the time.
But whenever I am holding him and put him down and he screams, I fight the impulse to pick him up in response. I know it's not good for him. I'll even say,"no crying" before walking away because he's learning some other verbal commands too about not touching stuff etc. After just a few weeks, he's stopped crying when I put him to bed, and he only lets out small angry shouts when I put him down, walk away etc, but he doesn't keep crying, because it doesn't get him anywhere. My daughter did the same thing, but got over it much quicker.
Don't EVER give in after a really long crying fit, because he'll learn to cry and scream a really long time. It'sno fun to hear crying, but you need him to learn it doesn't work to control you.
It's been given the name "separation anxiety", but the truth is, they just feel instantaneously mad or sad in the moment because they want something, and they are learning their power and how to get things. It's not a deep dark psychological medical condition in most cases. It's totally normal. It will be harder on him psychologically later if you don't get him secure with himself now. You know you are giving him everything he needs, and enough security and love, so be firm. Your son is just having a tougher time. Be patient, be firm. Good luck!