Hello dear.. Regarding the problem of Erectile dysfunction, it is due to decreased blood supply to the penis. Though medications like Sildenafil citrate (Viagra) increase blood flow to penis & maintains erection, It can be improved by having a diet rich in fruits, vegetables, fish, nuts & honey. You can also do oil massage of the penis...it increases blood flow & maintains the erection. One more thing...avoid consuming any over the counter medication which claim to increase the size of penis or improve performance...it may be harmful & regarding the injury to skin under penis, it is possible for the frenulum of the penis to get injured or tear during sexual activity. The bleeding is not much significant unless there is injury to the frenular artery. Healing usually occurs within two weeks. So...no need to worry about it. Wishing you a Healthy Life. Take care.