Yes, it is so hard to stay calm when it is one of our children. Sometimes we know too much and can't stay focused or over-analyze things. Our minds automatically go to the worst case senario. You should be relieved that the tests done so far are negative. Just try to relax and see what happens next week. Easier said than done. It is always good going into any appointment having as much information as possible. The more information you can give the doctor next week regarding trends in your son's vitals, the more he'll have to go on during his consult. Keep your log up and try not to worry too much while you wait.
Keep us posted, and know that you and your son are in our thoughts.