My kitty is mad at me! How do I get him to trust me again?

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My kitty had a bad respritory infection so I brought him to the vet. He's never been before, he's an outdoor kitty I take care of.It took an act of congress to get him in the carrier and he groweled and hissed at me the entire way there! He doesn't like it inside at all (i think he's scared of the walls) but still even though he's outdoors he's still my little baby, and I had to get him help!So he hissed and growled thru the entire vet visit to. He's normally very shy and sweet. When I got him home I gave him his meds and he took off.He didn't go far, but 5 hours later I'm still getting the "I hate you!" look. :( He won't even take his favorite treat from me.Even I leave it and walk away,he doesn't trust me anymore! How long does it usually take for them to get over it? My indoor cats have no problem with the vet or meds...