geterdun, I hunt Elk Neck as well. More specifically Carter, the same place you and your gf walked through. Those things are the size of the lead tip on a sharpened pencil. The main trail is infested with them as well as the grassy areas in Carter. One day last year, my roommate and I went scouting there. Afterwards, we were both infested with literally hundreds of these things on each of us. However, we did not notice them until the day after when My roommate felt something biting his ankle and as he looked more thoroughly and noticed hundreds of these things embedded in his skin. I also looked more closely and found hundreds on me as well. I do believe they are chiggers, but they look very similar to ticks- they are relatives of each other. this is a chigger:

Whatever you two had, good luck with that. Next time you get them, take duct tape and stick it to your skin and peel it off.This seems to be the most effectiveway to remove them. Showering does not take them all off.
Good luck. The whole part of North east, Md seems to be infested with chiggers and ticks. I go through atleast 2 rolls of duct tape a season on chiggers alone hunting Carter, Rogues, and Turkey Point. BTW, Carter is doing horrible. The first 4 weeks of the season only 3 deer were takin. I am not sure what is up to now, but I know it is producing much even with muzzleloader season.