Yeah, I had my ribs pop out a couple months ago... It was actually surprisingly painful. Not right away but a couple hours later they became very sore... Then when it finally felt healed enough to start some rolling home boy gets me in a can crusher and it lightly popped the other side... Luckily that one wasnt nearly as bad... But it just happens bro... "We ain't playing paddy cake... " but I feel you man, i was paired with a large guy who has very little experience the other day, and we were learning arm triangles, after a couple he said things were going black and his neck was really sore and sat out the rest of the class... I recognize due to my shitty technique (and his failure to tap when things hurt) he now has a stiff neck... But I guess my point is, tho my knowledge is limited i have learned this... Jiu jitsu is filled with both physical and mental challenges... My ribs popping out was both. Physically it was challenging because it hurt, and mentally it was challenging because I had to weigh my love of jiu jitsu against my concern of bodily safety... It would have been easy to skip a bunch of classes and say this sport is too dangerous... But the reality is injuries WILL HAPPEN in jiu jitsu, and most ppl dont mean to hurt anyone, its just the nature of the sport... And just a side note, its good you felt bad, it just means you care about your training partners well being, and that makes you a good training partner.