Weird smell up my nose...

I was lucky enough to be given the all clear in November following 2 yrs of treatment for colorectal cancer and secondary liver metastases. 

My question is has anyone on this forum ever experienced a 'funny smell' before they were diagnosed? I ask because for the 2 yrs prior to it being found I was driven mad by this smell, that I, but no-one else could smell... it was sort of a smoky cooking sort of smell.

Thing is, it went away following treatment, came back just before the liver metastases were found, went again following treatment for that and now it's come back again. I know the Dr's will think I'm mad if I say to them I think it's come back, so I'll have to wait for my next follow up bloods and scans in February...

Am I going mad?