Please Help-Atopic Dermatitis During Fall

hi everybody! I am new and not quite sure how to work everything on here yet, but I hope that I am posting in the right place.
My 3 year old weiner/lab is breaking out in hives, which I believe to be from atopic dermatitis- after all of the stuff I read online, that's all that seems to make sense. About a month ago he began itching on his back beside his tail,in the last week I started noticing red bumps appearing around his groin and back leg pits. I have been using a little cortisone cream the past few days and a topical treatment for hotspots the last week. He is treated with flea meds monthly, bathed regularly with the same shampoo he's used for 2 years, eats Blue Buffalo food as always and hasn't had any changes that I know of to cause him an allergic reaction.
Is there anything else I can try to do for him?
I am almost positive this is a seasonal fall allergy. Last year around this time he kept itching at his incision from being "fixed" and almost tore it open(he had been fixed almost a year before that and it was fully healed prior to this). I didn't know what it was at that time so I used the hot spot stuff I have been using this week and it cleared up within a few days. Now the same thing is happening this year but much worse.

Any advice would be much appreciated by my miserable itchy pup and I ❤