Prone masturbation & Premature ejaculati

Hi, I had been doing Prone masturbation from almost 12 year's ( frequency of masterbation is 5 times a month) and I never had any problems of erectile dysfunction and delayed ejaculation. But from past two to three years I am experiencing very sensitive frenulum(the part of penis connecting head and shaft of the penis on bottom side). Due to which if i am touching that frenulum part of penis I tends to ejaculate within 30 seconds no matter what how much I try to control.Other parts of penis have normal sensitivity also I did started to feel back pain after doing the prone masterbation. Also I do experience slight pain in penis after I did masturbation. Hence I quit this method also I quit masterbation from past two months but still I feel like I may experience premature ejaculation during sex due to this hypersensitive frenulum. Hence please advise what can I do to overcome this problem. Thanks