Do you have any allergies? Like hay fever, or allergies to plants, etc? My voice is the same way at times, and I have a really rare allergy called angioedema. Sometimes, that causes my throat to swell up inside, and it feels like a lot of pressure, and I cannot talk right or sing. I love to sing, but when this happens, it really makes a difference.
Also, have you had your thyroid checked out too, for any possible swelling? Also, any blood work done to make sure everything is okay?
My guess would be though, that you may have allergies to something, and you might want to sit down and make a list of everything that you may have changed or been around, such as perfumes, or wash detergents or softeneners, or soaps, or animals, etc. Even what you might have changed in your eating habits, could make a difference.
Also, do you smoke? That could cause problems. Or if you have been around someone or people who smoke.
God bless and good luck!