I look 5 months pregnant!?

Lemme start this out with me telling you I know for sure I'm not pregnant. I'm not fat in fact I had abs before this happened, I have no idea why but my stomach kinda just popped over the coarse of maybe 1-2 weeks it went from muscular to looking 5 months pregnant,(I don't feel bloated at all) I can suck my belly in and look somewhat normal but I don't understand why this is happening its been like this for the past few months and I hate it, does anyone have any idea why this is happening or what I can do to make it stop!?