Sexual laziness & confusn. Deficiency!

Hi, I would like to share some sexual issue with you and hoping a advice from your side. Myself a 26 year old guy works in a Bank in Gurgaon. From Last couple of months I am facing a little exhaustion between my legs. Felt less control, less erection and quick ejaculations. If you think about over masterbation, so its being frequent from last many years but didn't effect much as it now. I had a Breakup since then its itencity got high along with the lil addition of Porn. My sexual attraction got less and frustration got high. I realize these symptoms when I observe my morning erection are gone away and felt less/no power in genetal. I got anxious about this situation weather it's a psychological. I am also a bit overweight so I am worried if it is physiological in nature. As their are various misleading article on this topic on internet leads confusion. Please help me and suggest a way to find the root cause. PS: taking supplements for VitaminB-12 deficiency