Can the sense of smell get tired or lost?

Answer 1

Well accually no. Did your nose ever hurt because you kept on smelling? That's just normal. You wont lose it but if both nostrils are blocked, in one second, one of them will unblock (maybie 2, 3 or more seconds).

Answer 2

Yes,if your sick like with a cold or something,your senses get duller because they are being over worked by fighting the bacteria/virus or what ever it you may have.