Not that it will help you with last night's sleep ... but I take a Chlor-Trimeton (chlorpheniramine maleate, the little yellow pillls) pretty much every night when my allergic load is very high, on top of the immunotherapy and loratadine and Singulair.

Diphenhydramine (benadryl) never does much for me in terms of allergy relief, but it will definitely knock you out, and if it works for you as an antihistamine, it's another option.