Not gaining muscle very aggravating?

I'm 5'8 135lb age 21. I been workin out forever, years. And I haven't changed. I work my nuts off at the gym and I never ever get bigger. I eat a lot. I've done everything and anything nothings changed I'm the same size I've always been. I walk out of the gym looking huge for like an hour and than I turn back to normal size. In the long run I'm still the same... help?