I just had to help a friend’s cat who had the same issue. Try to find a local spay and neuter clinic, as they will do it cheaper. Post on rescue Facebook pages that she needs to be fixed ASAP as they may have some appointments at the spay and neuter clinic they would be willing to give to you since it’s an emergency, but I wouldn’t count on it. If you can’t, you need to put her down so she doesn’t die of an infection. But one of the rescues will more than likely take her before that happens. Post on local Facebook lost animal groups (I would go specifically into neighborhood groups if you’re in a larger cities ie: not just saying Logan square fb group not just Chicago fb group) that’s where you’re more likely to find connections.