Allergies vs Anal glands??

Question
My 8 yr old mix-(Pug/Scottish Terrier), had terrible skin allergies in 2000 thru 2002 treated with steroid inj and many baths (Dr's think it's from pollen, dust,etc.)  Last yr I controlled it with Benadryl every summer and weekly baths until this yr...July 25 she had to get the  steroid injection again(which i hate because she always has an accident)it helped for a while, but she started biting near her back end again constantly. Her belly doesn't look as red as before, but she does continue to lick/bite her paws and mostly anal area.
Because I have noticed  "wet spots/mucous like" near her anal glands lately...my question is could that also be her allergies or do you think i need to have the glands expressed?  
My dog nor I have got any sleep for weeks and I'm just not sure what to do. I can't tell now if it's still the allergies or something else going on.
Any advice is greatly appreciated.
Thank you
Sleepless in Rockford, IL

Answer
It is much easier with less side effects to use cortisone tablets to regulate the dog's response to itching rather than an intermittent shot.

Anal gland problems are unrelated to the allergies.  They should be expressed by the dog every time it has a bowel movement.  If that's not happening let your vet look at them to see if they need to be expressed or if they are infected.