Rescue cat, diarrhoea

[OntheWaves40]

I have a rescue cat, 10 yrs old. He’s been with us a month and has chronic diarrhoea. There’s been some small amounts of blood too. So he’s been wormed and had the pro bio paste. He’s now just started Hills ID wet food. Is there anything else I can be doing?
He mainly uses the litter tray but sometimes cries and then poo’s in random places. Could be anxiety? He always looks worried but has no probably sleeping on the sofa/my bed so can’t be that upset?

Have you given him nothing but boiled chicken and rice for two or three days? If so, what happened?

Do you know his history? Had he stomach issues st the rescue?

We got kittens from CP almost a year ago, they had diarrhoea. After vet checks etc we tried a grain free diet, which seems to do the job. Nb Sainsbury's own wet food, nothing fancy!

Does he cry right before pooing?