My DS hasn't had much trouble pooing before, but the last 4-5 days he's really struggled. He has pooed a couple of times, but usually he's v regular, always pops late morning and then 50% of the time poos late afternoon. He's really straining and struggling and often nothing happens.
Nothing has changed with diet, and he drinks loads of water.
My 14mi has the occasional issue. We normally give him a one off dose of lactulose and it usually does the trick. Also, does he eat a lot of wheat? After speaking to HV after a particularly bad episode she swig feared that too much wheat may be the issue. We cut it out for a few days and he was much more comfortable. Now we just watch his wheat intake (I.e not wheatabix for breakfast, sandwich for lunch and pasta for dinner!)