I am 46 years old and normally weigh about 135 and I have always had a flat stomach but over the past month I look like I am 4 months pregnant. I am not pregnant and have not changed my eating habits or my everyday routine. I cannot figure out what could be causing such severe bloating.

The stomach is above the navel. Do you mean abdomen?
No one online can possibly even start to guess at the correct diagnosis, and there are many choices.
You need to call around to clinics, or find yourself a regular MD, a good idea at age 46 anyway (I'm assuming you don't have one, or would have called).