Why Do One Experience A Strange Sound Coming From The Skull?

Hello.i don't know how to explain this,but for the past 9 months i have been experiencing a strange sound.it seems like it is coming from the base of my skull.the only way i can explain it is like pop rocks candy or the fizzing sound of soda.it started after i hurt my shoulder lifting weights in march.it happens with stomach growling,also sometimes with certain movements and wheni move my left arm up like im scratching my back.i do not have any pain with it.or headaches.other than the sound i lead a normal life.i went to the doctor,he didn't see anything.he said i had slight straightening of the spine.i want to know if this could be a CSF leak.like i said i do not have any other symptoms other than the noise. thank you. NICK. also sometimes when i swallow i will hear it.