Hello,
I highly doubt you did any permanent damage, but you may have become desensitized, or not as sensitive as you once were to the showerhead/bathtub. There are a few things you can try to help increase your pleasure. First try changing up your routine; maybe try using a toy (vibrator?) or different massage technique that you haven't tried before. Use your imagination, but don't do anything or use anything that could possibly cause any injury. Another idea that you should consider is taking breaks between sexual activity/masturbation for a few days, to help increase your sensitivity again. Keep in mind that not every orgasm is going to be as intense as the last; sometimes they can be mind blowing and then some not so much ~ that's normal for most folks...
Good Luck