Hi Anne!
I can shed some light on the allergy thing (and costs) because Brooky just went through it all with a dermatologist after TWO horrible allergic reactions in one month (face neck swelled to the size of a balloon) as well as a lot of other constant skin infections and allergy symptoms (scratching, biting, licking etc.). We have seen a neurologist too, who asked us to look at the allergy side of things for right now as she felt that needed to be tackled first (especially given the two horrible reactions she had a week apart from each other).
First...an average appointment with a dermatologist is around $350 (in Australia, assume it is around the same in the US). They will most likely want to do a skin prick test (Brooky had this done) and that costs around $380. The skin prick test will show airborne and contact allergies (but will not show food) and will show the severity. Brooky for one has a SEVERE (to the point when the pricked her they had to give her a counter shot to stop the reaction because it blew up) allergy to moths. Sounds like a funny one, but most likely she either ate a moth or was playing with one in the back yard the last two times her face blew up this month (because there were no signs of a stinger), so this is good to know. She also has a moderate allergy to grass, ragweed and cockroaches.
Now to answer your questions....well what do I do about this, you can't remove those things? Well, one option is doing a desensitisation shot therapy (you do regular injections over 6 months to a year of the actual allergen, you dermatologist will make up this solution) and you go through that process in the hope that that either stops or decreases the allergy in the dog (20-30% of dogs do not respond to the allergy vaccine, 20-30% response excellently and 40-60% respond partially). So you run the risk that you do this, but not much might happen. It is also a long course of therapy. The quote I got for the whole duration of this was $387.15 (but I will be doing the shots at home vs. at a vet to save money and the derm will train me on that). I have not decided if I will move forward on the injections or not, but wanted you to know the info an costs at least
We are also doing an anti-histamine trial (with over the counter anti-histamines) to see if they help or work at all. Anti-histamines can be of help with seasonal allergies.
For Brooklyn, we also have to carry an epi-pen and a VERY high dose emergency anti-histamine...but that is for her sever reactions (which are aweful, in 30 minutes flat she almost stops breathing and I had to be talked through doggy CPR last time!). So that would be less likely for you.
As for food allergies...the ONLY way to test for that is with a food elimination diet. You can do this at home, and while it might be a little pain to you to monitor food and cook some things etc. it is not a cost issue, can be done on your own and will tell you accurately if Elton has a food allergy to something or not. There are so many things dogs can be allergic to in food, that sometimes switching foods around does not isolate all of the allergens (in which case Elton would do slightly better if one allergic food was removed, but not 100%). Doing a food allergy elimination diet allows you to isolate exact proteins and carbs to really paint the picture. This is the easiest of the above, but aside from effort on your part, you are not shelling out a ton of $$ for tests etc. Just need to feed the diet correctly. Message me if you want more info on this, I'm on week 4 with Brooky
Also, does Elton lick/bite paws? If so, Epsom Salt soaks from the knee down for apx. 10 min will help that a lot and good to rinse off feet when you come inside if you suspect grass or something is irritating him. I keep baby wipes by the front door and just quickly wipe off Brookys paws.
Sorry, this was a LONG reply, but I wanted to give you all the info I had because I am in the middle of it all with Brooky. There is always the CM and other issues that can be causing things too, but this is at least some allergy info to add to your ever growing knowledge bank!
BIG HUGS to Elton!!