I had a penis enlargement surgery, since then when my penis is erected its softer than it used to be (did an ultrasound check but they found nothing)?

Talk with experts...: Why, how, and when did you had such surgery? Based on answers to the above question, an experienced urologist should be able to tell why it's and what you need now. But, in my experience, such surgery is rarely needed, probably never, especially for someone of 28. So, please go straight to ask your surgeon for detail about what you expect down the road. Best wishes...