How long were you running 90? Obviously if you just jump up from 60 to 90 (a 50% increase!) you are going to feel like crap for awhile until your body adapts. Try slowly building up to 90 over a few months and then sustaining it for a few years, then get back to us!
P.S. I know you are probably either a troll or lying about your time, but if you can run 14:10 off only 60 mpw (year round not in just in your peak) the 5k is probably not the best event for you, try the 1500.