IT - if you have a family doctor he won't have to examine you when the penis is erect. Let me ask you a couple questions:
How long has this been happening?
Any new medications?
Have you ever injured your penis?
When its erect, does it have a curve?
Does it hurt when erect?

Yes this can be a medical problem so tell a doctor and see what's causing this. Explain this isn't the typical hardness and its causing problems. If the doctor scoffs then explain this isn't funny to you. Here's a website that might be helpful:

Penis Pain: Causes, Symptoms, & Treatment