That's shed intestinal lining. I agree with Kathy, get them started on corid right away. It can be found in the cattle section at your feed store.
I'm thinking this might be a result of the report of MG in your birds causing these problems.
It appears there are tapeworm segments in the feces, if so, pumpkin seeds and wazine are ineffective. Wazine will only get rid of large roundworms. I recommend that you purchase Valbazen liquid cattle/sheep wormer to get rid of tapeworms and other types of worms your birds have. Follow this...