Back in May I trapped and had neutered, shots, etc several strays.
One of them I kept (Bonnie) several of them are still eating here
(attracting possums now, too dammit).  A black and white longish
haired boy has changed in the last couple of days.  He used to be very
skitterish and ran when I put food out only to eat when I was inside
for a while.  A couple of days ago he started to approach me when I
put food out and now lets me pet him.  Last night it was cool out so I
had windows open and he was diving at the windows clamping on with his
claws freaking out Shadow, Shamrock and Bonnie, howling like something
was wrong.  To keep everyone calm, I had to shut the windows and put
the AC back on.  He has a very gravelly, low-pitched meow but he has
always sounded that way. Its just that I haven't heard it to the
extent he is crying now.  He is trying like hell to get inside.  Now
when I'm at my kitchen sink he jumps up to the railing and claws the
window screen crying.  I've been out there several times to sit with
him and see if I can tell if he is sick, he is eating well and quiets
down when I'm outside and lays at my feet and loves being scratched
and pet.  I put some advantage on him and started trying to clip out a
mat on his rear end but he seems fine.  When he's out there alone I
can hear him meowing urgently.  What could this change in behavior
mean and how can I tell before it is too late if he got into something
toxic like fertilizer or got into some grass that someone treated with
pesticide?  Signs?

I'm a lil worried about him.