Glad it helps you get by! I hadn’t heard of the rotating antihistamines trick and was curious about the mechanism, so I asked Dr. DuckDuckGo. Could’ve always been some other tolerance mechanism, like faster breakdown of the drug, which rotating might help with. The paper does mention benadryl and a handful of other substances, but it’s also ancient by research standards, so I don’t know if that applies to all antihistamines or if some circumvent tolerance induction somehow.