What Causes Pain In Scrotal Sac?

Question: Hi, am XXXXXXX ..... I really don't know how to put this because it's gonna sound very very awkward and It's gonna be like...."eeeeeeww "....... owk, .. i've got this set of ballz.." scrotum" that's like really really getting on my nerves,...... This is how it behaves.." when am with this girl, .. and we are like horny, and I got her to have sex with me, it stays intact, .. I feel completely normal with no pains anywhere, .. but when we get talky, and horny, and while in the game, she stops me from having sex with her, or somthing close to that, ... my scrotal sac hurts so badly... the connecting tissues holding my balls intact swells and it feels big and turgid, .. like its forming another ball or somthing....... I can't really walk comfortably because of the pain......... now, . here's d funny part, .... after having a little sleep, .... the swelling stops and reduces, and the pain subsides........ NOTE.: it only happens when am bounced,.. or when am very close to doing real crazy things with her but didn't get. the chance...... bt apart from that, ... I can stay a whole year without any pain....... please tell me, .. what is wrong with me.... ? .... and what can I do to remedy the problem ..? It hurts so badly.