[Skin Concerns] [Routine Help] Husband allergic to a variety of antiperspirant deodorants! Recommendations please!

Hello SCA! I'm a longtime lurker needing a suggestion on an antiperspirant deodorant for my dear husband.

Within the last couple months my husband (26) developed an allergy to a variety of antiperspirant deodorants. His primary care physician prescribed him a lower strength steroidal cream (triamcinolone acetonide 0.025%) to aide in clearing up his red, sensitive, itchy, flaking patches which formed in both of his armpits from a contact allergy. So for twice a day for a week he put on his cream with nothing else and his pits cleared. He tried another stick he had in his drawer and the rash came back and he used his cream and it went away. He went on to use my antiperspirant deodorant which he had used plenty times before in the past and he flared up again, so another week of cream treatment. We went and got him another one which was unscented and for sensitive skin from the grocery store and again, another flare up. We aren't sure what ingredient is causing it!

So far he has tried:

• Old Spice Wolfthorn Men's Invisible Solid Antiperspirant & Deodorant (His original)
• AXE Phoenix Antiperspirant Deodorant Stick (Extra one of his)
• Arm & Hammer Ultramax Unscented Antiperspirant Deodorant (Mine)
• Tom's of Maine Naturally Dry Antiperspirant, Unscented

He has a known contact allergy to shellfish but we don't believe any of the ingredients are crustacean-derived so we're stumped. Nothing else in his routine has changed. He uses Softsoap Body Butter Shea & Almond Oil Moisturizing Body Wash and has for nearly a decade. He's a chef and it's 100*F out here so an antiperspirant is a must. Nobody likes sweat-seasoned food! He's not adverse to unscented, all natural, or things labeled "for women", and normally we share whatever deodorant is out on the counter top anyway. He prefers not to make it himself since always reapplies during the workday and carries a personal stick to fit in his knife roll pocket. We don't have a budget, but preferably less that $15.

Thank you!