first of all, i’m so sorry for your losses and all of your upheaval. that’s a lot to deal with all at once. i hope you’re doing okay.
secondly, he may just need reacclimation to your home. please try to be patient with him. my male cat was this way when i brought him home from the shelter…he was absolutely NUTS for a while. the only thing that really helped was increased interactive playtime, so i bought a wand toy and went “fishing.” that seemed to help.
if she’s had diarrhea for that long, you need to get her to the vet.