Pain in left hand side of stomach?

Im actually asking this for my boyfriend. He said he has a pain in his left hand side of his stomach. But its not actually his stomach, its just beneath it. Like his bladder. Ive researched a bit into it and the most accurate one that sounded most like his pain, was a pulled muscle. Which made sense to me, but he said he woke up with it. He also said that it hurts when he needs to urinate, but doesnt hurt when he goes, just feels like a huge relief when he does. He has also been urinting more, but not just little bits here and there, hes been going more frequently and urinating properly each time. When I searched these symptoms it came up with Interstitial Cystitis.

What would you say is wrong with him?

His symtoms are: Pain in the left side, just below the stomach, pain when urge to urinte.

Thank you!