Testicles Felt Funny and Twitch During Masturbation

I am a seventeen year old that would usually masturbate once a day. After one session I had noticed my testicles felt a bit weird (I can't exactly explain the feeling). They did not have any pain so I just ignored it and proceeded again the next day. After the second time the funny feeling got worse so I began to worry. I'm not actually quite sure if there was pain or if it was me being paranoid because it really had me worried for awhile. If there was pain it was so light that I could hardly notice. Again I waited a day and the funny feeling subsided, but instead I could then feel them as I moved, sat down, or when I was lieing down. I waited it out for awhile without masturbating and they have finally returned to normal however, when I masturbate I feel a strong twitch from them (usually near the bottom of my left one or the middle, not so much the right one). I'm not so sure about the pain again, if there is any it's very slight and hard for me to tell, again if there is than it subsides quickly though. I have scheduled a doctors appointment, but it's a week away. Can anyone tell me if this is normal? I don't think I've ever had such strong twitching sensations from them before during my sessions (though I'm sure there were). Just a note after I noticed the twitching I did finish one session and they were normal the next day (no funny feelings, but my left groin feels kind of pained). After that however the twitching seems to be worse than usual so I've stopped for the time being.