Hi! First of all - try drinking the same amount of water but reducing the high fiber a little bit. One misconception about constipation is that upping fiber helps, but if you are prone to skimping on water eating more fiber will actually make constipation much much worse. I tend to have the same issues, and I did feel that if I wasn't careful with my water intake on accutane it would become a problem so I was really careful about it. Try to drink about a cup of water (minimum) an hour for every hour you are awake. In the morning, I found that drinking a big glass of water (about 2 cups) before morning coffee really helped get the day started, if you know what I mean.

And, TMI, but don't be afraid to try a stool softner. Stay away from stimulant laxitives (like senna, exlax, or dulcolax), but an osmotic laxitive like miralax (or milk of magnesia if you need something to work a little faster) is safe to use until things become regular again. Also - try a good probiotic, it can help normalize things and keep you regular. Stay away from the cheap stuff though, those supplements are typically useless. Look for the refrigerated kinds that has lacto and bifido strains (bifido is especially important for people who tend towards constipation) - they do help to normalize everything down there.