I smell smoke from a fire which does not exist. I have been recording the dates and it happens about 4 days each month. When I think back when I was pregnant I couldn't go into a room as I thought it smelled funny and on other occasions I smelt weird smells no one else did. I think it is hormonal. I am on Hrt conti patches. I wonder if this helps or hinders? I have looked up phantomasia, it must be linked with hormones.
hi im on conti patches and I sometimes get the same, usually just before I would of got my period so its the progesterone phase. i have always had a sensitive sense of smell, and smelt cat pee when other people have smelt perfumes etc. 
Hi Jackie, thanks for the comment. That makes sense. It is reassuring to hear that I am not alone. 