That's really scary that EMTs would tell you that. Honestly, I'd report it to their supervisor. What if they told someone that who didn't know to ask others?
The only way to know for sure if a helmet is damaged is to X-ray it. If you're going to be laid up for a while (I sure hope it's quick!), contact the manufacturer; I think most of them will do that for free (motorcycle helmet manufacturers will, not sure about bicis). If it's okay, they'll send it back to you; if not, then you may be eligible for a crash replacement discount.