Shoulder has become suddenly weaker (but I feel NO pain)

Recently I’ve had a few little injures (nothing really painful) that have caused me to stop going to the gym for 2 weeks no. The main issue is my shoulder, when I do a bench press or overhead press my right shoulder doesn’t seem to have any strength and feels very half way through the movement and towards lockout.. I feel absolutely no pain whatsoever which actually annoys me more because I don’t know why this is affecting me so much. When I put both my arms up towards ceiling my right does feel slight more stuff but no pain. Can anyone figure out what this is? I go to the gym a lot a to just put it in perspective I can do 80kg overhead press for 5 reps, but struggles to get 1 with my current situation. Also, what might be connected is that I’ve had what I think was a knot in my upper back near the right shoulder blade for ages. At first is was it felt so tight and sore but has died down now.. but I can still feel something there and feels like I need to twist my back to crack it like when your crack your knuckles but I can’t.. also been getting slight muscles spasm in my back .. usually only happens for a few seconds and before I go to bed and when I wake up.. always been getting a few on my upper chest right side... it’s all on my side that makes me think things are connected .. also I hurt something near my RIGHT ribs/ intercostal / obliques kind of area... for a few days everyone I sneezed or cough it felt like someone was stabbing me in my side but that has died down too... but at the time I couldn’t do a single pull up without pain. This pain was the first to accure then the shoulder / back muscle knot came on at same time perhaps week later. Appreciate if anyone could shed some light on my situation thanks.