From the beggining

I adopted my cat from shelter at Jan. She is a 3 years old girl(This is the worst idea to adopt an adult cat). When she just got here, she was cute, friendly and elegant. And I later learned that she was a cat that had been spayed and neutered and then released back into the wild.I just don't know why she's in the shelter. I suspect her previous owner may have also noticed this personality issue of hers.

Symptom

But now, she has been a sensitive and aggressive. Based on the experiment, I asked my friend for petting her. It's fine. Then I tried to pet her when my friends are here. It's fine too. But when my friends left, she became more aggressive and sensitive.

Sometimes she wants me to pet her and she just walks around my leg. Then I will pet her back or head soft. This has been a habit until she attacked me suddenly. At that time she just walked around my leg as she usually did, when I pet her, she just attacked me. Now I have a scar on my back of head. She removed a part of my skin.

Issue

From the last month, I don't trust this cat anymore and she doesn't trust me too even I don't know why. When I just walk, she will hass me and run away. Totally confused me.

Do you guys have any ideas about this?