Hi, my hubby had the same problem through winter with the log fires as the tree sap triggers his hayfever. He was taking 2 antihistamines a day sometimes, and it was worst at night. Someone told us that if he drank Organic Nettle Tea sweetened with local honey it would help. He has a cup each day and doesn't take antihistamines anymore. It has to be honey made from the local area, fortunately we have a store that sells honey that is so fresh, it's still buzzing. I find the local markets sometimes have stalls that sell local honey - but not the supermarkets.
Neil says it's not the best tasting drink but he treats it as medicine, not supposed to taste nice as long as it does the job.
May as well try it, it may do the trick.