I know some people will give the chicken some olive oil if massaging the crop isn't working, it help lubricate what ever is stuck inside so it'll unstick easier. You can give it some apple cider vinegar in its water(1 tablespoon vinegar to 1 gallon water) to kinda regulate the yeast growing in it crop. If its acting at all lethargic I would, if possible, separate it and limit its food(let it have water though). Massaging its crop is great, have you just massaged the chicken sitting down or attempted what some people do whith their chicken upside down trying to get it to regurgitate its food(I know nothing about the method or its safety, so I can't say anything on it).there are some super helpful articles on here and videos on YouTube on how you can help your chicken get better. Best of luck, I hope your chick feels better soon!