Cat's belly leans towards the left

So, one month ago my 4 months female kitten escaped the house and stayed outside for a little more than two hours. When we finally found her, she was sitting in a corner, breathing heavily and being frightened. She was so frightened that when I picked her up she peed. Due to being very dirty I bathed her and noticed she had some bites, most likely from another cat as we do not have any racoons or something similar in our area. My vet was not open that certain day so I called an experienced lady and told her about the situation. She told me how to treat the wounds, which I did. About a day later the cat's belly was leaning towards the left, it was like it became bigger from only one side of the belly.((So pregnacy is excluded)) I called back the lady and she told me not to worry and that it will propably be gone soon. But it isn't...So is any of her organs destroyed or maybe misplaced? Is she in pain. And is it treatable naturally, with medicines or with surgery? If so, how much will it propably cost to treat it?

It sounds as if your young cat has had other injuries internally, or some kind of infection which is not yet getting in to her blood to cause other signs of illness.  I really don't know what it would cost for a vet consultation in your area, and as the possible causes are so varied give any idea on what treatment would cost.  However, it does sound like there is something significant going on and if you do not check it out she might suddenly become very ill, and you might even loose her if it is a pocket of infection.   Please do call and vet and ask them whether they could examine her.

You really need to get her to the vet for a proper diagnosis and to make sure she doesn't have an abscess or something like that.

If you are in the US, VCA vet clinic give a first visit for free.