Erection about every thirty minutes

Patient: I’m 18 and over the past 3 days I’ve pretty much had a constant erection. It doesn’t matter where I am, or what I’m doing. I usually get a full erection every 30 minutes and it lasts about 10 minutes each time. What do I do. I have tried to stop them by jerking off, but I’m hard again in 30 minutes. I’m losing sleep now, please help.