Hi there. I can fix these issues for you within 24 hours of go-ahead and receipt of access credentials.
With over 35 years' commercial IT experience, the last 20 as a freelancer working remotely with clients around the world, I've huge experience of leaping into "crisis" situations and resolving them promptly and securely. There are a number of reasons why you may be seeing these issues now and I wouldn't like to second-guess until I've seen the full code and examined the database. (The code you attached INCLUDEs, or refers to, other files that I'll need to review as well).
What I would need is full FTP access to your live website plus login details for your database (assuming it's MySql or SQL Server); if it's MS Access then I can simply download the MDB file over FTP.
I will of course take backups of any files to be changed before uploading the corrections and testing the fix(es). Whilst reviewing the code I'll also alert you of any potential issues that may cause further future problems.
There is a small chance that the issues are the result of an upgrade by your hosting provider; I think this is unlikely as other database functionality is working OK (although the site is very slow), but in that case it may be impossible to resolve immediately and some further discussions would be needed.
Please take a moment to review my feedback and ratings; I can assure you of a sound technical solution, great communication and outstanding value-for-money.
Regards,
Derek Pattenson