sexual intrusive thought making me doubt my career and think I am a horrible person

I have generalized anxiety with some obsessive features, i am a med student. The other day my physician was examining a 16 year old patient and I got a tiny amount of what id call a 'penile response' like not an erection or even arousal, more like a visceral reaction.

I was anxious and obsessing over this while laying in bed and because I was waking up I had a little morning erection as I was going over the incident in question. With my morning wood I like humped my bed one time (kind of like stretching?) like I usually do before I get up. Because I had been going over the incident and picturing it I like freaked out that I had been wanting to be sexual with that person (and with my anxiety who knows).

So i freak out that I shouldnt be a doctor because I must be a pedo. My girflriend asks whats wrong and I tell her she says its weird and gets mad I thought about another girl which makes me horribly anxious. Now I am fixated on her saying its weird.

What is really tough is I cannot tell if I did the 'hump' thing out of arousal for this person, or if I just did it randomly, and then got super anxious because I had been thinking about the situation. I cannot tell which is which. Thus I assume the worst, that I did 'hump' because I was sexually into what I was thinking about that girl. This makes me feel like I absolutely cannot be a doctor, that I am a horrible person, etc.

I know that in the future I will have to do all sorts of examinations on females young and old, even like pelvic exams and stuff. I worry that I am some sort of weirdo who shouldn't be doing this. I feel like I am a 'horrible person' for "fantasizing" (what my anxiety makes it out to be, it probably isn't true fantasizing) about a patient, yet alone a patient who is very young. I am sure in the future I will get random fleeting sexual thoughts, I am after all human.

Please help. I swear I am a good guy and not like a pedo or a perv