The first step should be for you, to the best of your ability, to avoid all allergens or reduce your exposure to all allergens to which you may, on the basis of experience or allergy testing, be allergic to. That would include both indoor and outdoor allergens and the concentration of the latter may be reduced with air-conditioning.
I cannot recommend a medication for you but will tell you that the so-called non-sedating antihistamines are generally deemed to be safe, especially at your stage of pregnancy , bordering on the third trimester.
You should definitely pose this question to your obstetrician, before you take any medication, prescription or over the counter.
I'm having the same issue with my eyes, I've used everything possible and nothing is helping