Please help if you can- kitten question?

i am an owner of 3 cats. they are well taken care of. up to date on shots. altered. fed well. etc. i have a house i share with just my boyfriend with plenty of space to have so many animals. so i dont want anyone to jump on me for being a bad pet owner please.

friday a family member came to be and asked me to take in an 8 month old kitten for her. her friend got this kitten for free without thinking and was going to throw it out her front door. it is winter here mind you. she couldnt take it home herself so she asked me if i would take it. im such a sucker for animals, so i did.

im worried about this new kitten. she sneezes a lot. she will get into these spells that she will do it several times at once too. she also keeps biting herself. she has a few sores on the back of her neck and a couple bald spots on her where it looks like she might have bit her fur off. overall she is eating. her poop is fine. she runs and plays like nothing is wrong. she does breath kinds loud from time to time. but it doesnt seem like she has trouble breathing and doesnt seem like her heart is racing or nothing like that. im not sure what is wrong with her and what i should do. i checked her for fleas and i dont see anything else in her fur. i gave her a bath with some baby shampoo thinking this may help if she has some type of skin allergy. i didnt want to use flea shampoo in case it would be to harsh on her skin. she is still biting herself but not as bad.

my problem is im between jobs and cant afford to take her to a vet right away. i dont want to release her to a shelter cause the ones in my area are always full and im scared they may put her down. any suggestions on what i can do to help her in the meantime till i come up with the money to get her looked at?