We have some of the best advisors right here, but they aren't always looking at these threads. I can try tagging them and see if one will respond. @casportpony @Eggcessive got time to look at this?
Clostridium perfringens causes a foul smelling diarrhea. If your hen had it a week ago, it progresses so rapidly that she would be much sicker by now or likely dead. I've never heard of it causing tumor-like masses in the intestines.
If it's not an egg stuck in her, then it's possible it's a...
It sounds like your hen could be egg-bound. The hard mass you are feeling could be an egg stuck inside her.
This can be life-threatening. If this has been going on for a week, and if she if egg-bound, she must be very uncomfortable. Is she pooping at all? If she isn't pooping and is still...