Can you develop an allergy you never had before?!

Yes. I developed allergies as a teenager that i did not have before.
I cannot be around some types of incense myself. It is generally the stick or cone variety that makes me a bit breathless. I make my own loose incense generally nowadays, and as long as there is a window open i am ok, so i presume there is something in the commercial variety that is causing the problem.

Absolutely. It is said that our bodies change every seven years, and frankly; I believe it. I never had any kind of allergies as a child, but as an adult I've found that I'm allergic to bee stings & pollen... I'd been stung by bees when I was a little girl and spent much of my time outdoors growing up and never had an allergic reaction until my late 20's. Don't be surprised to find that you're now allergic to anything that you once had no problems with. Have you switched the brand of incense you'd been using? Keep in mind that even if you're using the same kind of incense; they may have changed the ingredients or added something that you're sensitive to.

Yes you can. It's how allergies come to be, they develop.
I didn't used to be allergic to several things I am now. Developed my allergies in my adult years.
It happens.
And just so ya know, you shouldn't burn incense sticks, as the smoke has been shown to cause cancer in some studies.
If your wanting scents to fill your home, your better off with potpourri tarts and a warmer.

Actually you can. Because you explore more foods, that you don't ever have tasted. The more you grow old, the more you have been to paces, trying things that are suitable for age know that your old, your trying tampons, condoms, whatever pills you take. Trying new things, is good, but make sure to slow down in trying them..

allergies develop in different ways. for example, if you don't clean your room/apartment the buildup of dust can cause you to get dust allergy.