This is a classic presentation of a cat with an upper respiratory disease. They usually do have a fever early in the infection and will feel bad. They also tend to avoid eating and drinking, because the congestion in the nose does not allow them to breathe properly.
You can help the congestion by giving him a steam bath (if possible). There is a link below that has good information about how to do this and other helpful tips for this condition.
http://www.wikihow.com/Help-Your-Cat-Breathe-EasierUnfortunately, we cannot (legally and ethically) advise medication without having an established patient-doctor relationship. It is also dangerous for us to advise medication without examining Miss Kitty and fully understanding her condition and medical history. I do not recommend giving the penicillin for this.
It would be best if you can get Miss Kitty to a vet within the next day or two, but I understand you are unable to catch her. You may consider getting help with this, or hiring a cat trap. While these infections are often due to a virus, they can become complicated with bacterial infections, which will make things much worse. The vet would be able to prescribe the necessary treatment to make her feel better and keep the infection from getting worse.
I hope that helps and Miss Kitty gets better soon.