x2
In California the University of California Davis, in conjunction with their veterinary program, has labs throughout the state where they will accept chickens which have died or been euthanized. The standard necropsy is free and very comprehensive; additional tests are available for a fee. The standard test would identify if worms are the problem; it seems like worms are usually a side condition as a result of the main problem.
While you are looking for a possible source of necropsy, it is standard procedure to triple bag the chicken and place in a refrigerator, not freezer. I have found the extra large ziplock baggies (2 gallon?) work well for hens, maybe for roosters too. I have been advised to ship in a double box and include an ice pack next to the chicken.
Sorry for your loss therrychicken, hope the next step is rewarding.