go4drhunting - I think you have been getting some good info, but I believe your main problem has not gotten addressed yet. I think your problem could be multifaceted, but I also think the main problem lies within your placement of the tag. I of course have not seen where you are placing the tag, I'm only going by your statements and my experience of doing what I believe you said you are doing.
Sounds like , if your tagging as close to the head as possible, you're likely tagging into more of the 'meat' of the ear than you should, and you need to be in-between the ribbing of the ear and approx. half way to 3/5 of the way out on the ear from the head to the tip, and 1/3 of the way up from the bottom edge of the ear. This position works well because A) It places the tag in a thin area of the ear with no flesh/meat, only cartilage, and B) allows the tag to lay in a position to cause the least amount of friction to the ear because you are placing it below the curve/cup of the ear.
One year we tried changing locations of our tags. We moved them lower and closer to the head. We did this to allow a quicker and clearer reading of the tags as the deer got older, cause as the deer got older and their ears grew and their hair grew, we had trouble reading our tags. That year we had ALL KINDS OF TROUBLE with ear infections and lost fawns because of it. I incorporated 9 or 10 people that year to help me catch each and every one of my fawns to remove the tags, treat them, and put in new tags in new positions. We had ears so infected that they stunk with rot...because they were indeed rotted.
Here's what we have always done and RARELY had trouble after that one particular year:
1) We started by making sure we had tags designed to ward off infection (not sure how key this is , cause we used these kind of tags the year we had all the trouble, but it can't hurt).
2) Dipped the stud of the tag in alcohol
3) Thoroughly cleaned the front and the back of the ear with alcohol
4) Then, as you have already been advised by others, wiggle and pull the stud lose from the female part so it's not bound, and then spin the tag in the ear to make sure it's not bound there either.
5) We always, along with our other shots, gave the fawn a shot of Draxxin as well.
6) And of utmost importance, and as I said before I believe to be the main source of your problem, make sure you get that tag placed in a thin part of the ear, absent of flesh, and placed solely in cartilage between the ribbing of the ear.
This has been what has worked for us and has worked well. When I said ''RARELY'' did we have trouble, let me spell that out more clearly. Out of 40 to 50 fawns born and tagged each year, 1 fawn every 3rd or 4th year or so, MAYBE, would come up with an infected ear.
Hope this helps and hope the best for you and your deer...God Bless!!!