It's straight forward because you are new. There are several different techniques. Darting vs slow/steady. Going in at an angle vs straight, Inter muscle vs subQ.

You hit a nerve more than likely going in. You also may have injected to quickly. It's best to take your time, 1 minute per CC otherwise you are blasting it into a muscle causing a charlie horse.

Ba = Benzyl alcohol, one of the compounds used in making the gear. If the concentration is to high it can hurt.