Is it normal to have have these spams when sexually tensed?

Okay, so There is this this girl I have been talking to for a while. We usually just talk to each other and that is it, but recently things have began to escalate. Especially now sense she had to temporarily move out of the city to help with some family, Me and her usually talk through skype and one night my A/C broke and my house got so hot I took off my shirt and pants, (I wore gym shorts) but I did this in the middle of the call, but I was laying in my bed talking to her and she started talking mildly dirty to me which I was okay with me but then, she takes off her shirt and she pulled down her bra and that was fucking it. My heart rate started increasing rapidly, my body started burning up and I was having these all over body spams, I couldn't talk, my teeth were jittering, my legs torso and arms were just spasming like Hell. but after a while she put her shirt back on and these weird spams stopped. what is this about? Can I please have a scientific explanation to this. thank you

(this is a little bit more information that might help)

I have had offers come up to me for sex multiple times, and each time I could easily say no, same thing with dating, but this girl is different. I want to be with her, I want to make her happy. She is the only girl I can't refuse.