Joined: Aug 2009
Posts: 6,717
Likes: 5,340
From: Minneapolis
Bikes: 2022 Salsa Beargrease Carbon Deore 11, 2020 Salsa Warbird GRX 600, 2020 Canyon Ultimate CF SLX disc 9.0 Di2, 2020 Catrike Eola, 2016 Masi cxgr, 2011, Felt F3 Ltd, 2010 Trek 2.1, 2009 KHS Flite 220
Old helmets in which the foam has been compressed (not necessaraily from a crash, but those occasional times you drop them, etc.) don't absorb impacts as well.
Also, helmets have improved a lot in the last 11 years.
Get a new one.