Soo Idk What's Happening But Recently My Left Testicle Will

soo idk what's happening but recently my left testicle will hurt like a mf and then when I put vaseline on it then it goes away, today I went to get an STD test but I won't know anything till the 19th.. I haven't had any sex since that incident and ion know what is going on. This only has happend 2 times and the first time was like almost like 3 weeks ago and then like 2-3 days ago it happend again. I'm scared and ion know what to do.