When my allergies are really acting up, I too, sometimes get what the doctors have referred to as "allergy shiners" and have had it happen to only one eye before if that is the side of my sinuses that is the most congested. I'm not exactly sure why it happens, but my guess is that when your sinuses get inflamed and congested that perhaps they kind of press on the blood vessels under the eye and since the skin under your eye is so thin, it looks like a black eye.
I would say (but I'm no doctor, so consider that also) that unless you are also experiencing signs of an infection, such as fever or colored discharge from your nose/eyes, etc., then it more than likely is a result of your allergies. Try using a cool compress on your eyes when you're resting at night and sleep with an extra pillow to help alleviate not only your sinus symptoms, drainage from your sinuses, but also any of that blood from basically pooling under your eyes.
I feel for ya - my allergies are driving me nuts also. I live in Virginia and the pollen levels here have been outrageous!
Hello,
Since you have been having sinusitis since so many days and now a bruise, so although it looks less likely but a cavernous sinus thrombosis needs to be ruled out. It is due to formation of a blood clot within the cavernous sinus, a cavity at the base of the brain and the infection may spread to this sinus from other sinus infections.
An examination from an ENT specialist is required.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your dermatologist. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.