Seriously do at least a few sessions with a PT or a trainer and make sure you are using correct form and strengthening the right combination of muscles. I went through something similar and it got pretty debilitating. You don't want to mess with your neck.

I have recurrent shoulder issues on one side and I am constantly modifying. There are so many ways to work on your shoulders without ever directly lifting vertically. That was self guided advice I confirmed when I went to see my sports ortho after I got back into the gym weight lifting last fall. In my case the AC joint gets inflamed and off we go to the popping. It’s from playing third base and pitching through high school.

For the shoulders you can do lateral and front raises with a dumbbell. If you have access to a gym you can use a cable machine and also lift a plate weight in front of you. All those shouldn’t irritate the shoulder. I’d also be careful with any pressing overall and maybe even avoid incline. You can do weighted push ups instead.

Be very careful in movement and use heat and stretching. Press your shoulders away from your ears, no rib flare and keep the core tight.

I get neck stiffness from it also, but it’s partially because those muscles are weak and need strengthening! Consistent lifting even if it’s light weights is important. But above all, do it safely.

I tend to overload into my traps instead of using my lats. Be super conscious if you are doing this and scale back on the weight.

check your form. When you do shoulder presses are your elbows straight-out to the side/ in line with your shoulders? They should be at more of a 45 degree angle from your body to protect the shoulders.

Overhead lifting movements are not a good idea if you’re a newbie.

yes. I balance it out with back/neck stretches/SMR. I like to end each upper body workout with a long forward fold while grabbing my elbows, swaying side to side and mentally trying to let go tension in my neck/shoulders. When it's loose enough, it can feel my spine/neck adjust. Or you could go to restorative yoga.

Ever since I have started doing strength training on upper body, my neck is in pain and cracking and popping like crazy. In general, I feel like it's destabilized--no radiating pain or numbness. I am going really light and not overdoing it at all: 5 lb for shoulders and tricep and 10 lb for bicep. I'm really conservative on movements above the head precisely because one of my shoulders is tight and pops a bit. I have a feeling this is from shoulder work, which I never would pursue on my own and it's what's new in my workouts (it's part of the Peloton routines, whereas before I just did straight bicep and tri work). I'm going to try dropping anything shoulder and see if that helps. Anyone else experience this?