Hi and WELCOME to YT
! Sounds like you've been through a lot w/ this kiddo and that the issues could be interrelated / complicated....I say that bc it sounds like it could be a combo of both structural issues as well as allergies. When/if you throw allergies in the mix, it can get very confusing as to what's causing what.
Are you sure at this point if allergies are present? Or still guessing?
I wouldn't stick w/ Benadryl if you do think it's allergies...it doesn't work for allergies in most dogs, and it has a very short half-life which means to be effective, you have to give it every 4-6hrs (3-4x per day). Other OTC meds used in allergies for dogs are Zyrtec and Claritin, both of which are 24hr meds, which is easier. Again, they don't often work all that great, but work for some rare cases.
For further reading and treatment of allergies, read here:
http://www.yorkietalk.com/forums/die...tart-here.html