Allergy Pup

So i'm looking for an allergy shampoo for my dog that actually works. She's a bully mix, about 10 months old. She's had allergies since i got her 5 months ago, but they were very manageable with baths and salmon oil. But the cold weather has been awful for her allergies, if she so much as goes outside when it's cold in the mornings she'll come in with hives. So i decided to try a new shampoo specifically for allergies. I tried the "top recommended" Vet's Best Allergy Itch Relief, gave my dog a bath, followed the instructions, left it on for 3ish minutes like it told me to, rinsed thoroughly, and dried her. And less than 20 minutes later my dog was COVERED in hives on her back and ventral. She's not itchy or red, just with little bumps everywhere. Which is one of the primary symptoms of her milder allergic reactions, her worse ones normally involve red and watery eyes, and red rashes on her ventral. Which I'm not seeing yet from this last bath/ reaction from the shampoo. So the "top recommended" allergy shampoo gave my dog an allergic reaction. The shampoo i used to use wasn't giving her any adverse reactions, but it wasnt medicated either, it was just made for sensitive skinned dogs, so it wasn't helping much with her allergies either. I give her supplements, salmon oil, and bathe her twice a week, but especially lately with the changing weather her allergies have been awful. It's something environmental to the outdoors, because she's always perfectly fine at home. I give her 50mg benadryl (as prescribed by the vet for her weight) when i notice her allergy symptoms making her uncomfortable, but if I can find a good medicated shampoo i feel like it would help her greatly. Any recommendations would be great.