Well, after thinking that I had finally shaken off long Covid at the end of May, I'm now thinking that my celebrations were premature. My senses of taste and smell are definitely still compromised, I'm having to have a post-lunch lie down most days and my domestic auto-pilot is going haywire again. And, bizarrely, I seem to be experiencing phantom odours for the first time - I keep getting wafts of asparagus-pee smell without a spear having been consumed. It's now eight months since my infection...
Geordie, it seems that many people who experience parosmia & phantosmia do so months after Covid for some reason. It's supposedly part of the healing process of the olfactory nerve, but extremely frustrating (I had a very minor case which didn't last long but it was concerning at the time so I feel for you).
Have you tried smell training? You can buy kits online (cheaper on Ebay I found), and it's supposed to help. My smell/taste issues didn't last long - I took a concoction of multivits, Vitamin C, turmeric, bromelain, quercetin, probiotics and lion's mane mushroom (on your advice for the brain fog!). I also drank lemon & ginger tea as well as green tea (because coffee smelt & tasted foul to me for a while). I can't really say if any of them worked other than the fact that I got better, but I may have done without them too.
The only other thing I read online during my search for help was that ivermectin has helped people to cure both long Covid and smell & taste issues - within a short period of time too. I didn't try it so can't vouch for it personally but if you get desperate it might be worth giving it a go.