Feel guilty about thinking of rehoming my cat

I bought a pet off of Craigslist (an 8 week old kitten.) yes I know Craigslist is not the best place to buy animals. I received the cat and the owner did mention she was being treated for fleas. I thought no big deal. Well it’s been a couple weeks now and she has way more problems then just a few fleas

*Ear mites to the point where the insides of her ears are completely brown and crusty and she is constantly scratching them and leaving residue everywhere

*Digesitive problems. She goes poop (and I am not exaggerating) at least 10 times a day. And her poops are huge to the point where I am constantly changing her litter 1-2 times daily. If I don’t my entire room will smell horrible. I have to leave the litter box in my room as I share a bathroom with my roommate. She also passes gas a lot and will have a weird smell from time to time. I have already gone through a full container of litter in a couple weeks.

*To say she had a slight flea infestation is an understatement. She literally was covered in fleas and I spent $40 on Advantage which has helped a lot but she still has fleas.

I am also pretty sure she has worms as she is constantly hungry, and I have had to buy more food than I anticipated.

My other cat who is 11 years old never ever had problems like this. She is completely healthy and has only had one problem where she got bitten by a rat and needed antibiotics.

I am taking my kitten to the vet on Sunday to get looked at and im worried about a huge bill. I am not really going to rehome her, I do love her and she is bonded to me. But wtf. The previous owners never let on any of this stuff about her.

🙄Yeah because assume it’s so easy to get a pet appointment right now?? My state is still in lockdown. I got the closest appointment I could. I am not irresponsible, they are for selling a sick cat. If I was irresponsible I would have given her away. Thanks for the input though.