3 year old with strange bowel movements

My son is 3 and a half years old and for the past few days he's been complaining of a tummy ache prior to a bowel movement. THe bowel movement is not diarrhea, but not 'his' normal either. It's flaky and powdery. He doesn't need to strain much. Color ranges from light brown to dark brown.
Today while urinating, he let out a glob of yellow mucus. (no blood), just yellow.
Other signs about him: He has been urinating more than usual, sometimes twice within an hour. It's not uncontrollable. He's always been a good water drinker.

He urinates a lot at night. Still uses nighttime diapers, and even tho i've cut out milk and water at night, his diaper is well loaded in the morning.

Has been restless at nights, talks in sleep, checks to see if i'm around. Has complained once in the night about a tummy ache.

He used to be more inclined towards holding bm, and not wanting to go. Now it's the opposite, he gets the tummy ache and has to go.

As a baby- very very colicky, and even tho he was only breastfed, he didn't have bowel movements for days at a time.

Behaviour: Loves company and attention. Doesn't like to play on his own. Loving and talkative when in a good mood. When doesn't get what he wants, cries. Not aggressive.

Please someone help.