Re: Disease ID help . . . Foulbrood?
From your description, especially the yellowish look and the orientation in the cells, it sounds like EFB. Treatment recommendations are to treat w/ Terramycin and to requeen. But if this is a weak colony, I don't know if requeening will bring it back from the brink. You may have to combine what you have w/ a stronger colony. If for nothing else other than to protect the equipment from wax moth and SHB.
ps: sacbrood appears as a larvae in a papery waterfilled sack. If one stuck it w/ a toothpick it would break apart. I didn't see or read anything which suggests that to me.
"It's not what you look at that matters, it's what you see." Henry David Thoreau, Mark B