@Jill ******
okay from what I can glean from this convoluted story, the O/P got a NEW 45 day visa exempt entry stamp on Mar 18th with an expiration on May 1.
This means the CAN go to the immigration office and get a 30 day extension on it for 1900baht (seeing as you can get a 30 day extension once on EVERY entry and they don't have one on this stamp yet)
That gets them another month without the hoop jumping to "get a medical extension" because of covid.
Good luck to the O/P, get the 30 day extension you're allowed. If your story of entry, etc is correct, you don't need to get an extension based on medical reasons