I am not aware of any relationship between ALS and increased sensitivity to odors. Intermittent changes in smell can occur with migraines or seizures. Loss of smell can occur with trauma or destructive mass lesions. You have not mentioned your medication, but that would be something to consider (possible side effect). Sorry I could not be more help. Good luck.
Just one more thing to add, the increased sense of smell seems to makes my throat clamp shut cutting of my air way.
Also to add to this problem, when I touch certain materials such as fur, clothing, etc... it also takes my breath away just like the increased sense of smell does. Even when I wash my face and dry it, my face goes dry and again I cant breath until i put cream on.
I know it may sound stupid but it feels like my skin cant breath.
I know als is not meant to affect sensory signs but my als seems to do just that.