As I get older the lower end of my voice is deteriorating. I can still sing as high as I always have but it's my lower range that isn't what it used to be. I also can't seem to make interval jumps like I once did. When I was 47 I was in an accident and had to have surgery. They put a breathing tube in me and after surgery my voice was hoarse. Since then the lower end of my range has been a problem. I haven't heard of voices going higher as you age.
Nor have I. Based on your description, the breathing tube is more likely the culprit, not your age. I'm 52 and have my low register intact! I have temporarily lost my low range because I've dried my vocal chords out (drinking coffee before I sing or speak - I do voiceovers as well! ) and this may also be why your low register isn't functioning, that said, it really sounds like you may have some damage to your vocal chords, I'd suggest a ENT take a look down your throat, specifically your vocal chords to check for damage!