Breathe!
Logically you know you do not have rabies. You know that you are prone to hypochondria and reading things online will cause you to "see" the symptoms in yourself. As someone else has pointed out headache and sore throat are the systems to everything including allergies (starting to get warmer near you?)
The BEST thing you can do for yourself is to sit down with a pen and paper and write down all the reasons you do NOT have rabies. People have helped you with a few reasons.
1. You went to the doctor and they had no concerns.
2. Chances of catching rabies from a cat scratch are very slim.
3. It happened a month ago without any advance symptoms
etc......
Write the whole list as many as you can think of. Every time you feel yourself starting to panic, try going into a room where it is quiet. Start reading the list from the start and slowly and calmly breathe while reading each point. If you finish and still do not feel better start from the top and read them out loud. Retraining yourself how to think about the situation will help you have fewer attacks and hopefully you won't have the panic attacks anymore.
Good luck, hope that helps.