I've had my allergy/sinus issue since day 1 of my pregnancy and still going on to this day at 18 wks. I took benadryl only at night and suffered during the day. My doctor recently recommended for me to switch to sudafed (6hr) and to sleep slightly elevated. Once I did, it was like instant relief...except when it wore off. I was told I may have this issue up until she's born. Tissues and Sudafed are my best friends. Good luck!
Oh boy i hope i dont go another 20 weeks like this :-/.
Last pregnancy, I got a stuffed up head at 10 weeks, and it lasted until I had my son, I lived alternating zyrtech and Claritin, but the day I had my son it cleared up like it was never a problem, good luck