Do you mean her crop is swollen? On her right side of chest is crop, is it mushy feeling or solid? Or that she is swollen below her vent on abdomen? Check her for egg bound, glove and lube finger to check for stuck egg in vent. If you feel an egg, soak her in warm water, give her calcium tablet to help her expel egg. Massage her abdomen gently toward her vent while she is soaking to help move egg. Dry her off and have her in a warm dark place to give her a chance to lay egg.
After you check her over for crop or egg problem post your findings so we can assist you.