Inappropriate defecation

[doggyman]

I have five cats, two blind, one deaf, one with very low immune system, and one very timid. The older blind cat (Buddy) has never been very friendly or sociable, the younger blind cat (Charlie) is more friendly but can be wary. Recently Buddy has been aggressive towards Charlie to the extent now Charlie tries hard to avoid Buddy and has started growling at times at the other three. Also lately one of them, I suspect Charlie has on several occasions defecated in and around their water bowl. I use a feliway diffuser and also give the two Bach flower Rescue Remedy. Since I moved the water bowl the defecating has stopped but someone, again I suspect Charlie continues to spray it has been reduced from three different areas to just one I clean with vinegar and water or Simple Solution. The cats do not live in the house, I have two dogs and would fear for the cats safety, the cats are in a large shed in my back garden which is like an annex of the house. Due to having been ill recently I haven't been out with them as much as I used to but have now started getting out with them more and the problem seems to be easing does anyone think the problem has been me not getting out with them enough or because Buddy has been bullying Charlie or a combination of both. Any ideas gratefully received.