Not really familiar with ph's, mostly use test, but I hear cramping/painful pumps can be a big problem with some compounds. Taurine seems to be the reccomended solution, though I've never heard it described as a sharp pain. Is it usually when you workout or just random? Have you been doing very heavy bicep lifts? It's possible that you're strength and weight lifted has increased too fast for your tendons to keep up causing inflammation and possible injury. If that's the case I'd lower the weight because you do not want to tear something.