Can Medication Interfere with Diagnosis?

I posted this question in response to an article somewhere on this site about neurological exams, but, in the interest of getting answers, I don't mind being redundant, so here it is again, with more background info: I have been struggling for many years with episodes that no one has been able to explain. Last year I was sent to a neurologist. I have since been referred to second neurologist and, subsequently, an epileptologist. I was placed on an anti-epileptic some time ago, and it controls my symptoms, 'though dosage as had to be adjusted many times. By the time I was referred to the epileptologist, I was on this medication for over a year. The epileptologist has said the result of my neurological exam was inconsistent with epilepsy. If the medication controls symptoms, would it impact the outcome of that exam? I've been to so many doctors, and am just trying to make sure I am getting the right answers. I'll add more background here. I have been having a number of different types of events for years. After reading a lot of the information available here, it sounds to me like I am experiencing absence seizures (if any of these things are seizures at all), as well as some other type of thing I haven't quite figured out, but I do suspect it is a type of seizure. I have to rely on other people's descriptions of what happens during them, because I can't tell you what happens at that time. Basically, I fall on the ground and am unresponsive for a very brief time. Eyes and mouth are apparently open, and I am just sort of frozen, 'though no one has given me an answer on whether I am stiff as a board or slack. I know that, for me, I remember that I am trying to walk/talk, I feel weird, out-of-it, disconnected kind of from thing, and then I just find that I am on the ground and people are gather around, and I think I should say something to them. When I try to talk, seems a little...like, monotone, almost robotic to me at first, but then I start to feel pretty normal again. My husband has told me I am just "out" for about 15-30 seconds total when this happens. It has happened very often at events like rock concerts, specifically when we are down on the floor, close to the lights, speakers, etc. There will be a moment when I feel almost like I am transfixed, and then I have that weird, disconnected feeling, and then I think, "oh, no, here it comes! I need to get out of here..." and I will try to make my way out of the crowd, but I feel all strange and like I am not walking right, and I usually don't make it very far before I fall. It has sometimes happened in other situations, as well; and I have sometimes had the feeling it was going to happen, and been able to get to a place to sit or lie down, so I didn't fall, but just kind of sat or lay down, and stayed there until it passed. I had one EEG, which was normal, and then I was placed on Topamax, and it seems to be controlling the symptoms. I am not 100% sure about the first ones I mentioned, because I really didn't even know that was happening until very recently. My husband was talking about it one day ~ about how my face looks when it happens, and I thought he was describing how my face looks when I fall (it's apparently pretty much the same) ~ and I thought we were talking about the episodes in which I fall. It turns out there's this whole other thing that happens, and I didn't even know. :( When I mentioned it to my daughter, she replied, "Oh, yeah, you do that, all the time. Like, especially when you are on your computer." When I read about absence seizures, it made so much sense to me. There have always been times ~ even back to my childhood ~ when people have accused me of staring at them, or when someone was waiting for an answer and I didn't know a question had been asked, or I just felt like I had missed something. I old the epileptologist all of this, and she replied, "Well, I wouldn't make much of that." So, I'm trying not to worry. At least the medication is working...as far as I can tell!