Nasal sprays and other allergy medications are very safe medications that have very few side effects. I can think of no reason that using these medications over the summer (months ago now) would somehow have damaged the inside of your nose in any way and led to this problem you are having now with a strange burning smell inside of the nose.
One possible explanation for this strange smell is that your allergies or sinus congestion have crept back and are now bothering you again. In this setting, it is fairly common to have disturbance in your ability to smell, which could lead to either decreased smell or the perception of a strange smell (which is what you are describing).
I suggest that you get in to see your primary care doctor
as soon as possible. They can perform a thorough examination and help figure out what might be going on. If there is strong evidence of nasal allergies or sinus congestion, they will probably want to begin with treatment of those and see if the problem with the burning smell improves.
They can also evaluate you for evidence of rarer, but more serious, causes of strange smells, such as a seizure disorder or a tumor.