I don't think it's your dogs and here's why I think this. In many cases, a person builds up a resistance to whatever the allergy cause is. Your husband has presumably been around the dogs for quite some time so it's doubtful that he would become allergic to them. It would be the other way around--by now, he would have built up a resistance to any allergen they put off.
I speak from experience. About ten years ago my doctor tested me for allergies and the results of the test astounded him: I was allergic to everything in the test except for fish, eggs and chicken. If I remember correctly, the tests covered 2500 items. He calls me Allergy Girl and says he's never seen a patient as allergic as I.
Consequently, I have around 10 years of dealing with all types of allergies.
The tests showed I was allergic to cats. I have two cats--a black one and a white one with spots. Black cats produce the most allergen. Yet after awhile, I had no allergies to my black cat and I can even bury my face in her fur with no consequences.
So I think you can let the dogs back in.
I would, however, get rid of the carpet. Also, get a mattress cover. Our mattress and box springs are covered in plastic to prevent dust mites. We also have dust mite pillow covers, etc. You should check into the bedding thing by doing some research. Possibly search terms like "bedding dust mites covers," that type of thing.
Your husband should dump those OTC allergy sprays because they actually can get him hooked. This becomes a never-ending circle: the OTC spray perpetuates nasal congestion and the person uses more and more to try to overcome the stuffed up nose. Again, I speak from experience. I was addicted to them and it took about six weeks for my nasal passages to get back to normal.
There is only one kind of nasal spray that allows use without addiction and that is Flonase. It takes about a week of use to start showing results, however. Also you have to get it from your doctor. It's very good.
An allergy pill you may want to check out is Zyrtec. Lasts for 24 hours.
Finally, I think this season there is some odd type of allergen out there. I have heard a lot of people talking about how their allergies are really bad now. I am experiencing the same. In fact, right now I am having a frightful allergic reaction on my neck, chin and on up to my ears. It itches like crazy. For weeks I've had all types of symptoms, including nasal drip, coughing, etc. Zyrtec and Benedryl have been very helpful.
Tell your husband to hang in there--it will probably go away one of these days soon. Also, be aware it takes awhile to overcome addiction to nasal sprays.
Cher