Alright, so since I have started trying to get more fiber in my diet as my doctor told me to, I stopped having 1 big BM a day. Now I have 1 in the morning which is not too big, but it is soft. Then later in the afternoon I have a smaller one that is hard. What could cause this? Not enough water?

Possibly. What are you taking for a fiber supplement and how much water are you taking it with. Remember things like metamucil need to be mixed in a full 8 0z glass of liquid. You also need to take in plenty of water and other liquids throughout the day. Also it may take a while for you body to get adjusted to the the fiber routine so give it time.

How long have you been eating more fiber? If less than, say, a couple of weeks, it could just be your body getting used to the new regime.

I have been doing it for about 2 weeks, although on the weekends I didn't get as much fiber as before.

The biggest change was that I started eating breakfast(high fiber cereal), and because of that I have started getting BM's in the morning instead of afternoon. Before I didn't have breakfast at all and had just 1 BM in the afternoon.

I agree. It is simply a question of balancing fiber and water. You should be getting both insoluble fiber (as from your breakfast cereal) and soluble fiber (as from many fruits for example) to get the right balance. Soluble fiber is a stool softener but if you take it in the form of Metamucil or Citrucel for example you must drink plenty of water otherwise you will have problems.

How much water should I drink with a high-fiber cereal for breakfast?

You should drink 8---8 ounce glasses of water daily.

I think my body is just adjusting to eating a new meal(breakfast for fiber purposes) which has changed the time I have a BM. When I first started eating the cereal i nthe morning I had a second BM (normal size) later, but over time it has gotten smaller and harder until today I only passed a few small hard pieces of feces. Does this sound like my body adjusting? I hope it isn't anything more serious