Hi Ari,
Wool allergies or sensitivities are generally contact allergies or sensitivities and it would be unlikely that they would be an issue used in an encasement in a topper, but with your sensitivities it could be such that the odor alone is disagreeable to you and causing your discomfort. For some more information, there is more about wool allergies or sensitivities in post #2 here and in post #4 here. While the odor generally dissipates over time, there is no guarantee that what is bothering you will do so at such a level that you will eventually find it acceptable. People with Multiple Chemical Sensitivities (MCS) often, unfortunately, have similar issues.
Phoenix