My cat is very friendly but starting today, after I let him back inside the house after about an hour of being outside, hes acting strange he hisses when I pet him or try to pick him up.... he doesnt try to claw or bite tho hes just hissing, I tried to give him his nightly wet food meal which usually makes him go insane while im still opening the can but he wont even eat it.... why is he acting like this? hes never done this before?