in addition to erectile dysfunction medication please also pick up a copy of 'PE How to Overcome Premature Ejactulation by Helen Singer Kaplan, MD, PhD. the combination of medication and the book would really help you heal. it sounds like you need rest, not sexual activity. your overclocking your reproductive system.
take care
Go see a urologist, only a doctor can determine the exact cause of your problem and prescribe you a adequate treatment. Viagra is very effective but it's not the only solution available today.
Saw palmetto has no use in erections.
Consider consulting a urologist as meds such as Viagra would likely work very well for you.