KHorne, did you get bitten again? R was bitten the other day and had major allergic reaction. They bite me and don't even swell. From everything I read, it sounds like the allergic reaction is to the anti-coagulate which the female deer flies inject when they are biting, to keep the blood flowing.
They are very bad this year, all over the Gulf coast of FL. DEET doesn't seem to prevent them from buzzing you, but it might help keep them from biting. I have created a formula which seems to work very well at repelling them.
Use a spray bottle and fill almost full with white vinegar. Add essential oil of lemon, eucalyptus, and rosemary. Not only do they cut the smell of the vinegar, but they are natural insect repellents. Shake well before spraying. Also seems to work well to keep the flies off the dogs. This formula also works fairly well in fighting dog flies and mosquitos.
I suppose you could also make a salve using bee's wax, olive oil along with the three essential oils, to make it last longer.