It would be good to know the details of those upgrades:
1. What exactly did that person do regarding a "clean up"?
2. What OS was on the machine prior to ?Yosemite?? And how long had you been using that OS?
3. How was the upgrade done? Was it a "clean, fresh, virgin" installation of that newer OS (unsure if it was Yosemite), or was it an upgrade in place?
4. I suspect the upgrade to Sierra was done "in place". If that's the way the prior upgrade was done, that can cause issues. Too much upgrading "in place", versus a clean, fresh installation, is not good.
5. If you use any third party software, it most likely needed to be upgraded also, to be compatible with the newer OS.
6. How exactly are you getting to that University of Portland site? Are you using Safari?
7. Are you making backups to an external device? That is crucial.
Good luck with trying to get useful information from the folks at the IT department for the school. In most instances, they know very little, if anything, about Macs. A "remote" possibility is that the software on that site is not compatible with Sierra (and, it seems, with the OS that the Mac person upgraded your machine to) and/or the version of the browser you are using (that's why I asked in question 6 above). It would be best if you find out from that individual the answers to the first three questions I mentioned above. That also could help when you call the school's IT department.