Allergists will always tell you to start with a nasal spray because locally acting medication has fewer side effects than systemic meds. You can try a steroid nose spray, but there’s also Astelin, which is a somewhat newer OTC antihistamine spray.
If you need more, take an oral second-generation, non-drowsy antihistamine LIKE Zyrtec or Allegra. You can even take one brand in the morning and another with a different active ingredient at night. Talk to your doctor, but adults can double the dose on many of the H1 antihistamines. People do it for MCAS. Read the cautions about such medications for pregnant people, the elderly, and patients with glaucoma.
You can also try vitamin C supplementation. It helps the body clear out excess histamine.
If you’re still suffering, you definitely need to talk to a doctor. There are prescription medications that can be used with OTC meds. Also, allergists are generally going to recommend shots for people who have symptoms in spite of taking meds.