i've found out why i premature ejaculate

last night, while i was having sex with my girlfriend, i realize what makes me ejaculate so fast. First i thought it was my mind, that somehow i get nervous and ejaculated, although, i always, and i repeat, I ALWAYS get calm during sex. But the what makes me cum prematurally, its not a psycologic issue, but a physical problem, to be more especific, its in the middle of my penis, where i have a scar from a procedure to remove the frenulum. Now, knowing that, what is the traetment to cure this psysical trigger to ejaculate prematurally?