I Lost my Upper 3rd Tray of my Invisalign After 5 Days, Can I Go to Tray 4 for the Uppers Until I the Bottom Catches Up?

If you only wore the 3rd upper tray for 5 days, you should go back to wearing tray #2, and have your dentist order a replacement tray #3 which you will begin to use as soon as it is received,

I would do what you suggested. Call your Dr and get in to see him whem he comes back. He might want to remake 3 tray for you.

Probably you can do this. But I would contact your dentist for sure to determine.  It's hard without knowing the specifics of your case