Olfactory hallusinations

Recently I've been occasionally "smelling" odors that aren't there. The odors are generally not unpleasant, and they are always appropriate to the situation or my thoughts: I'm on my way to see someone who's fond of sweets, and I "smell" chocolate. My feet feel damp, and I "smell" sweat. Etc. The odors seem totally real for a very short time.
They don't bother or frighten me, but I'm really curious as to what may cause them??

I'm a female, age 47. No diabetes, exercise regularly, no signs of infections. Excellent health always, except breast cancer (op/chemo/rad) two years ago and a short Ciproflaxin treatment in early June due to long-term dry cough (lungs still feel 'sore' but x-ray was clear). After the Ciproflaxin I lost most of my sense of smell for a month, but it returned and is working well.

I gather there may be a connection between temporarly losing my sense of smell and later having these hallucinations, but I can't understand how a "nose-related explanation" could induce situation-relevant hallucinations???