Last year someone kindly threw 3 light sussex hens over our allotment gate, 2 were killled by a dog but the remaining one seems to have very runny poo, her bum feathers are all dirty and when she poos it just splatters out! She is healthy in herself and still laying eggs. Could it be the new grass that is starting to grow, none of my hens seem to be eating their layers pellets or could it be worms?