Have they visited outdoors yet?
If not I would bring in a dish of dirt from your yard or a clump of grass with roots and dirt attached. They will party! And it will help them to build some immunity to stuff in your soil before going out full time. My birds are often out by the first week with a huddle box to escape the sun or wind and feel more secure and warm up together. My weather rarely ever reaches 65 degrees in the dead of summer, so we are talking in the 50's as early as 3 days with no heat lamp.
And note that out of 9 strains of cocci only 1 presents as blood in the stool. Not saying that's it, just sharing info.