My cat won't eat!!

My 9 year old cat is off her food.
We originally took her to the vet for being over weight(16lbs), and and eating all the time. She gets very constipated also with very hard bowel movements even though we gave her Petromelt daily.
Changed her food and she would not touch the new wet or dry food.
We tried for 3+ days and she ate very little to nothing.
She was on Clavamox for infection but starting throwing up. So we are now switching to Baytril.
Problem is now I can't even get here to eat her old food. Even with tuna juice added. She is not lethargic and drink some water. But I am getting worried about her.

Any advice will be greatly appreciated.

When Twitch wouldn't eat, I tried Pink Salmon. It smells really strong. Over how many days did you switch foods? Can you add some of her old food to the new stuff to get her to regain interest? I found that switching dry food first, getting the cat to eat tat, then switching the canned food works best. Maybe give her the new dry food & the old canned food?

I am sure someone else will come along shortly that will be more help than I am. Good Luck & I hope she feels better soon!

She must go to the emergency vet IMMEDIATELY. This could be a life threatening situation. I don't mean to sound harsh but this is truly an emergency situation.

When an overweight cat goes more than a day or so without eating, it can quickly cause feline fatty liver syndrome. This is a medical emergency and is fatal without treatment.

Please take her to the nearest 24 hour emergency hospital right now. Keep us posted.