Pebble poo, should it be dark

[0879]

I've had this issue for a while now and it's constantly on and off. To try and improve it I've been eating fruit, exercising in the morning and drinking like 6 to 7 glasses of water a day. But in the days of doing that I've had 2 days of not needing to go and today having little dark pellets again. The other week I did pass a large stool and might have caused an anal fissure due to sour and itchyness at first but symptoms gone now. Other than feeling like i need to go but can't. About a year ago I believe I had some kind of piles as I remember wiping blood and feeling it. But that had since been gone for ages now. Any help?