stomach bloats up all month until my period, not with period

Good Morning,

I am not sure if it is lack of exercise or something wrong but my stomach has become enlarged. I am a 33 year old mother of one. I have had a blessed figure up until now. It seems as if my stomach bloats up all month until my period is about to start and it goes down. It's like the opposite of what most women go through. The average woman get bloated during the period time.

I am excersing at least three times a week for a hour.

Please advise.

Yolanda