1999 Honda Accord Gas seems to be disappearing, no matter w

I usually get VERY good gas performance, I can make trips to town [about 30 mis round trip] and my gas meter would barely move. But here in the past few months it seems like my gas has been sucked up no matter what. I recently got the tired changed, oil changed, I changed the air filter, and the tire pressure in the tired is good. I don't know what else it could be. I was thinking a hole in the gas tank, but there is no leakage on the ground at all where I park. I don't know what else to do, and the gas has run down to half a tank already after only driving around about 75 miles or so. Please help!