Gas tank won't take gas

I have a 2002 Pontiac Sunfire that is almost on empty and it spits the gas out as soon as we try to put it in suddenly. We looked and there is nothing inside and my husband used a snake type thing to make sure nobody had shoved anything inside and there's nothing in there. It takes gas but you have to put a tiny bit in and let it go down and then a little more. It takes like 20 minutes to put $10 worth of gas in the tank. Any suggestions as to what the problem may be?