It can be blackout due to fluctuations in blood pressure. You have not elaborated if the sexual act is painful for you.Also have you succeed in completion of sexual act? The very first incidence has underlined  feelings and awkwardness. It could be some  stessful body posture  or rapid breathing  or bearing  weight of your  partner thus hampering  respiration. Every  next episode  causes strong response  due to previous  experience.

Hi.. This could b a psychological symptoms. Of of fear n anxieties . Homoeopathic medicins could do very well in these cases .. Plz refer to homoeopathic physicians.. Or cal me.. or consultant with us.. Both counsellings n medicins will surelt gives results.. regards Deep Homoeopathic clinic

Hello Friend, Good that you are seeking a help here. One of the symptoms is sudden increase in BP. Pls consult a general physician to get a manage it. Other possibilities is psychological factors like fear, anxiety or stress. Sexual relationship or act  creates a lot anxious thought or fear which influence body condition by causing palpitation, dryness, tension, nervousness, over excitement etc. This is called as performance anxiety and due to that you may face problems like yours. Be positive. You should learn the ways and techniques to mange your unnecessary thought and stress. By following certain daily routines, specific excersise, self therapies, yoga or exercise along with a couple counseling guidance you can overcome both stress and anxiety. Feel free to reach me online or call for further assistance to manage your anxiety and stress. Be positive. You will be alright soon.

Hello, Consult a physician. It can be due to sudden drop in blood pressure or change in heart beat during  change in position.