WOW your story sounds almost identical to mine sadly
here is some info
http://www.yorkietalk.com/forums/yor...y-what-do.html
has your dog had a full thyroid panel all 6 as mine has hypothryoid and that is very important to have had done and it can drop alot in one year as my girl went from .78 to .30 in one year and normal for a yorkie would be 1.0 T4FREE but you need the full panel to completely rule out hypothyroidism - it needs to have T4FREE, T4, T3FREE, T3, T4AA, AND T3AA so check all blood work to see if you see this as an add on as hairloss can come from this
atopica is safer to some degree but they are linking to cancer now so it has it's risks but if it works great then safer imo than steroids but my dog vomitted it up after a year of being on it
my dog is on 1/2 temaril p every other day as well and per derm, ims, and vet that is the safest way to do steroid long term use and it is a very low dose. We also have blood work twice a year and she has been on it for 2 years.
Sounds like if you are in an area that has snow a mold allergy in winter so have your home checked for mold as my friends dog just dealt with this and she found mold where her dog was laying. Also when you turn on heater it blows out dust so before using heater get the hypoallergenic air filters for your unit. We use oreck air purifiers in the room she is in and i just bought the ROOMBA from costco yesterday to run daily on our hardwood, tile and laminate floors to get all dust up daily as they can be allergic to dust mites.
The safest thing is hyposensitization shots and that is the one thing i avoided and now sorry i have and reconsidering it as it works 75% of the time and most natural. I have been afraid it would make her worse but who knows i guess worth a shot. I would deal with derm on this and since your dog has been on steroids then you would have to wait 6 weeks or do blood testing which i will do if i do it and use lab VARL, HESKA OR GREER - i would seriously just deal with dermatologist on this as i do and ours is very good.
Allergies are the WORST thing i have dealt with and it started at 6 mos and she is now almost 6 - she is hypothyroid, mvd and atopic dermatitis.
from reading everything sounds like you have done it all like me except i did not see you post the 6 panel thyroid nor the hyposensitization shots. Allergies start at age 6 mos to 3 years. Your goal is to keep them as comfortable as possible but you cannot avoid meds sometimes as to me a short happy life is better than a long miserable one.
hang in there you are not alone

it runs in this breed due to poor immune systems and it stinks