It is quite likely he wants to mate the females and they aren't submitting to him yet. 40-50 hens with 2-3 roosters is a great balance. It sounds like he should be very happy there. Every time I've brought a chicken home they've stayed stagnant in weight or lost a bit. The stress of a new environment, different food, the new pecking order, possible illnesses the chicken wasn't exposed to in their past flock, all of it takes time to get used to. Then, they bounce back in a month. I do not know what the wound on his comb could be from without pictures. I know it's hard to let him be in the hands of someone else, however, I think you found the perfect place for him to be happy.