Hmmm... altho it's true men tend to lose a little length w/ age, it seems very unusual to lose that much so quickly, and also, I don't think most guys notice any change by age 40, more likley late 50s or past 60. My first thought is, did you experience any type of injury to your penis? And since you mention Peyronie's (which is a bending when erect), that often results from injury, so the two could be related. Another question: Is the loss in size only when erect? Meaning, is the flaccid state any different than before? Also, are your erections as full & rigid as they were before this issue started? It's possible something happened (injury?) that decreased blood flow to the penis, so that the full erection is not as big as before & possibly less rigid. I think there's a slight possibility this could be reversed somewhat - maybe not back to where it was, but possibly regain some of the lost length. There are devices which reduce the bend in Peyronie's (they apply a continuous 'stretch' that both straightens & might slightly lengthen the erection). One thing you should know - if you're at 5.5" with reasonable girth, you're still about average. Altho it was previously said the average erection is about 6", that data was mostly self-reported & how guys 'measured' themselves wasn't consistent. More recent (and more accurate) measurements say it's closer to 5.5", so maybe you can take some comfort knowing at least you're not 'small'. Good luck, hope you find a solution for this...