Has anyone had all of a sudden problems breathing during competition? I have always been a mid distance (200,400,500 and 1650) swimmer and I have seen my times add all season. I just can not seem to get the same air I did last year.

It's very possible that it is the pool. Ask your coach if the pool has had its filter inspected recently.

Well, other possibilities to breathe harder after a break of swimming (lets say week-2),cigarretes or canabis,or even the place you are.For example,my hometown is 1800m high to sea level and when I go to competition in one of the meets(where the pool is right next to a beach)I feel like I take a lot of oxygen and I swim very good.On the other hand people from lower lands have problems with breathing when swimming in mountains.I had the same problems when I was in another city for like a month,when I came back,I found it pretty hard to breathe.