if you're taking pain killers the pain might be injury due to bad form or other issues. agree with neek. should consult specialist or a doctor at least

having a positive mindset would help. everyone has injuries before i'm sure. its how fast we recover from them. Training by FEEL imo its not something you can learn overnight. Basically shift your mindset from: I need to do x amount of sets today to; gonna push myself until my body screams at me to stop. thats my own opinion btw, trying to learn from the seniors here also .